bluuebunny/crossref_metadata_2025 huggingface dataset:
Variable-angle dry etching with a hollow cathode
Authors: Horwitz Chris M.
Published: February 2003

Previous experiments have shown that very high etch rates can be obtained with an rf hollow cathode reactive sputter etching apparatus. This letter shows that hollow cathode etching also permits profile control, without mask undercut or mask erosion. The angle of etching is here varied from 90° (i.e., normal to the etched surface) to 50°, at a constant pressure of CF4 and a constant applied rf voltage, by varying the etch conditions. The etch angle is largely independent of the etched material (SiO2 or Si).
New low dark current, high speed Al0.48In0.52As/ Ga0.47In0.53As avalanche photodiode by molecular beam epitaxy for long wavelength fiber optic communication systems
Authors: Capasso F. , Kasper B. , Alavi K. , Cho A. Y. , Parsey J. M.
Published: February 2003

We report a new Al0.48In0.52As/Ga0.47In0.53As avalanche photodiode with separate absorption and multiplication regions (SAM APD) and an undoped spacer layer in the gain region. These devices grown by molecular beam epitaxy, have very low dark currents (4 nA at the onset of gain) which compare favorably with state-of-the-art InP/Ga0.47In0.53As SAM APD’s. Avalanche gains ≊60 and a high speed of response with a gain-bandwidth product ≊10 GHz are demonstrated. Receiver sensitivity measurements at 420 Mb/s and λ=1.3 μm with a Si bipolar transistor preamplifier yielded −36.0 dBm at a 10−9 bit error rate.
Metalorganic vapor deposition of CdTe and HgCdTe epitaxial films on InSb and GaAs substrates
Authors: Hoke W. E. , Lemonias P. J. , Traczewski R.
Published: February 2003

Heteroepitaxial films of CdTe and HgCdTe have been grown on InSb and GaAs substrates by metalorganic chemical vapor deposition. The CdTe growth temperature was 440 °C and the HgCdTe growth temperature was 410 °C. Specular CdTe films were obtained on (110) and (211) InSb substrates and (100) GaAs substrates. Specular surfaces of HgCdTe/CdTe/InSb and HgCdTe/CdTe/GaAs heterostructures were also obtained. X-ray diffraction measurements indicated that the heteroepitaxial films were single crystalline. The growth plane of the CdTe films on InSb substrates was slightly misoriented from the InSb orientation. The heteroepitaxial films deposited on GaAs substrates replicated the substrate orientation.
Be-implantation doping of GaAsxP1−x/GaP strained-layer superlattices
Authors: Myers D. R. , Biefeld R. M. , Fritz I. J. , Picraux S. T. , Zipperian T. E.
Published: February 2003

We present Hall-effect measurements of the first localized p-type doping in GaAsxP1−x /GaP strained-layer superlattices achieved by implantation of 1×1015 cm−2, 75 kV 9Be+ followed by controlled-atmosphere annealing at 825 °C for 10 min. The acceptor activation (∼15% at 300 K) and the mobilities in the p regions (∼20 cm2/Vs at 300 K) are consistent with the values expected for type-converted GaP-based alloys. Depth-dependent structural characterization by ion channeling demonstrates that the superlattice structure survived the implantation and annealing without loss of layer strain. These results demonstrate that Be implantation can be applied to produce localized doping in a strained-layer superlattice system and reflect favorably on the stability of strained-layer superlattices under particle bombardment and thermal cycling.
Negative differential resistance at 300 K in a superlattice quantum state transfer device
Authors: Kirchoefer S. W. , Magno R. , Comas J.
Published: February 2003

Negative differential resistance has been observed at 300 K in a bilevel superlattice structure. Additional experimental data from conventional superlattice devices verify that this negative resistance is due to transitions in the bilevel superlattice. These devices demonstrate that the Hess real space transfer effect can be extended to the quantum well regime.
Low-noise microwave field-effect transistors using organometallic GaAs
Authors: Aebi V. , Bandy S. , Nishimoto C. , Zdasiuk G.
Published: February 2003

The fabrication of low-noise GaAs field-effect transistors on material grown by organometallic vapor phase epitaxy is reported. Detailed descriptions of both the materials growth and the noise figure measurements are given. rf performance for the 0.35-μm gate length devices is given from 4 to 18 GHz, attaining a 1.9-dB minimum noise figure at 18 GHz with 9 dB of associated gain.
Current-voltage characteristics of a Si-BP-Si double heterojunction
Authors: Sugiura Souichi , Yoshida Tohru , Shono Katsufusa , Dumin David. J.
Published: February 2003

Si-BP-Si double heterojunction was obtained through the alternate growth of BP and Si on a Si substrate. After BP was grown epitaxially and then covered with Si3N4, it was heat treated at the stoichiometric temperature of 1050 °C. Thermal emission Ohmic current and thermal emission field current were observed for the n+Si(epi)-BP-n+Si(sub) and the p+Si(epi)-BP-p+Si(sub) structures, where the BP is depleted. Analysis of the current gives the barrier height of V0=0.4–0.6 V and an electron or a hole drift mobility of μ=70 cm2/Vs in the BP depleted.
Transmission electron microscopy and high resolution electron microscopy studies of shallow (R
p∼20 nm) As and B implanted and electron beam annealed silicon
Authors: McMillan G. B. , Smith David J. , Gowers J. P. , Ahmed H.
Published: February 2003

Shallow (Rp∼20 nm) As and B-doped layers in (100) silicon, formed by low-energy ion implantation, have been investigated using conventional and high resolution transmission electron microscopy before and after either electron beam or furnace annealing. After annealing residual defects were observed in the region beyond the original amorphous/crystalline interface for both As and B implants and the nature of these defects and their stability was found to be relatively insensitive to a variety of annealing conditions. Lattice images of 10-keV As-implanted material indicated that a continuous amorphous layer was formed after implantation which regrew into perfect single crystal following electron beam processing for 1 s with a peak temperature of 900 °C.
Disorder-activated modes in Raman spectra of Al0.3Ga0.7As encapsulated with Si3N4 films
Authors: Kamijoh T. , Hashimoto A. , Takano H. , Sakuta M.
Published: February 2003

Raman spectra of single crystal Al0.3Ga0.7As encapsulated with Si3N4 have been measured. The encapsulation is observed to alter certain low-frequency spectral features below 250 cm−1 associated with the disorder-activated mode. The enhancement of the disorder-activated mode intensities is attributed to the breakdown of symmetry selection rules by the strain field induced by the dielectric overlayer.
Oxygen in zone-melting-recrystallized silicon-on-insulator films: Its distribution and possible role in sub-boundary formation
Authors: Fan John C. C. , Tsaur B-Y. , Chen C. K. , Dick J. R. , Kazmerski L. L.
Published: February 2003

Using secondary-ion mass spectroscopy, we have found that oxygen is strongly concentrated at the sub-boundaries in zone-melting-recrystallized silicon-on-insulator films prepared by the graphite strip heater technique. This observation suggests that the formation of sub-boundaries during recrystallization may be caused by constitutional supercooling resulting from the presence of oxygen that is dissolved into the molten Si zone from the adjacent SiO2 layers.
Emission spectra, surface quality, and mechanism of excimer laser etching of polyimide films
Authors: Koren G. , Yeh J. T. C.
Published: February 2003

Emission spectra in the visible and ultraviolet range, and scanning electron microscopy of polyimide films exposed to 193, 248, and 351-nm laser radiation were used to elucidate the mechanism of the laser etching process. It was found that rough laser etched surfaces, with nonuniformities larger than 0.5 μm, are accompanied by a continuum emission from the blow-off materials, while smooth surfaces are characterized by strong C2 emission in the A 3Πg→X′ 3Πμ bands. Smoothly etched surfaces were obtained for all laser wavelengths provided the energy absorbed per unit volume in the surface exceeds a threshold value of (5.0±0.5)×104 J/cm3. It is suggested that surface smoothness results from transient melting and that the laser etching mechanism is mostly a statistical thermodynamic process without complete energy randomization.
Cleaved-coupled-cavity lead-salt diode lasers
Authors: Lo Wayne
Published: February 2003

A simple technique has been developed for the fabrication of lead-salt cleaved-coupled-cavity diode lasers. The improvement in spectral purity and the reduction in threshold current of these coupled-cavity lasers will be discussed.
Characterization and optical properties of arrays of small gold particles
Authors: Craighead H. G. , Niklasson G. A.
Published: February 2003

Square arrays of 20–35-nm-diam gold particles with 50-nm spacings were formed on thick sapphire substrates by electron beam lithography. After annealing at 125 °C the particles had an approximately circular projection on the substrate with a slightly smaller dimension in the perpendicular direction as inferred from scanning electron microscopy. Optical transmission measurements were made on 15-μm square areas of particles using an optical microscope modified for microspectroscopy. The regular geometry of the well characterized samples makes possible a detailed comparison to theory.
Electrical properties of selectively deposited tungsten thin films
Authors: Metz W. A. , Mahan J. E. , Malhotra V. , Martin T. L.
Published: February 2003

Tungsten thin films were selectively deposited onto silicon surfaces by a low pressure chemical vapor deposition process utilizing, sequentially, silicon reduction and then hydrogen reduction of WF6. Surface selectivity and conformal coverage of microelectronic structures is demonstrated. X-ray diffraction and Auger analysis indicate the films are well crystallized, with the possibility of a fraction of a percent oxygen content. The room-temperature resistivity is ∼18 μΩ cm, composed of residual and intrinsic contributions of 12 and 6 μΩ cm, respectively. The Hall effect indicates the material is predominantly a hole conductor, with a relatively low Hall mobility that is consistent with the large residual resistivity. Difficulties with a simple interpretation of the Hall effect are discussed.
Metal-amorphous silicon-silicon tunnel rectifier
Authors: Yang E. S. , Hua Q. H. , Yang D. K. , Yang G. S. , Ho P. S.
Published: February 2003

We report a new metal-semiconductor thin-film diode with an I-V characteristic similar to that of a p-n junction. Its forward bias current is dominated by majority-carrier tunneling, and its reverse breakdown voltage is over 50 V. The fabrication process, the I-V curves, and the Auger depth profile of the interfacial layer are presented.
GaAs/(Ca,Sr)F2/(001) GaAs lattice-matched structures grown by molecular beam epitaxy
Authors: Siskos S. , Fontaine C. , Munoz-Yague A.
Published: February 2003

Epitaxial growth of GaAs/(Ca, Sr) F2/GaAs structures by means of molecular beam epitaxy has been demonstrated. It has been shown that it was possible to grow layers with good crystalline quality and no noticeable interdiffusion at the interfaces. In addition, the uppermost GaAs layers present interesting electrical properties, exhibiting electron Hall mobilities of about 1300 cm2/Vs.
Effect of layer size on lattice distortion in strained-layer superlattices
Authors: Brown J. M. , Holonyak N. , Kaliski R. W. , Ludowise M. J. , Dietze W. T. , Lewis C. R.
Published: February 2003

The accommodation of lattice mismatch in strained-layer GaAs-InxGa1−xAs (x≊0.27) superlattices grown by metalorganic chemical vapor deposition has been examined as a function of layer thickness using transmission electron microscopy. The degree of distortion from cubic is shown to be dependent on the layer thickness and at sufficiently large layer sizes (≳180 Å) dislocations are introduced at the interfaces.
Ferromagnetic resonance imaging using photothermal deflection
Authors: Netzelmann U. , Krebs U. , Pelzl J.
Published: February 2003

The local variation of the ferromagnetic (FMR) resonance absorption scanning along the surface of ferromagnetic metallic films was studied with the photothermal deflection technique. Using a modified commercial electron paramagnetic resonance spectrometer the FMR of an inhomogeneous Ni film was measured as a function of the external magnetic field and laser beam position. The local resolution which depends on characteristics of the laser probe beam and on the thermal diffusion length of the surrounding medium was investigated at different modulation frequencies between 35 Hz and 1 kHz.
Power law broadening of charge packets at semiconductor interfaces
Authors: Cooper James A.
Published: February 2003

We derive a general equation governing the behavior of charge packets at semiconductor interfaces under the influence of drift and diffusion. We show that the width of the packet increases as the cube root of time when the differential mobility is positive and the charge density is greater than a critical value. For smaller packets, the width increases as the square root of time. When the differential mobility is negative, packets whose density is less than the critical value expand as the square root of time, while larger packets tend to contract. These results indicate that surface time-of-flight and microwave absorption experiments are feasible above the threshold field in III-V semiconductors, provided certain criteria are met.
Preferential diffusion and orientation effects of Schottky barrier GaAs field-effect transistors
Authors: McLaughlin K. L. , Birrittella M. S.
Published: February 2003

Preferential diffusion and the corresonding orientation effect was examined for GaAs Schottky barrier field-effect transistors. Unreported orientation effects of devices with no n+ implants are presented and compared to self-aligned n+-implanted devices. Characteristics of the intrinsic and extrinsic field-effect transistors were measured for devices oriented in the [011] and [011̄] directions. Enhanced diffusion due to anisotropic stress is proposed as the mechanism. Criteria for preferred device orientation and ambiguities in previous literature are discussed.
Optical and electrical oscillations in ferrofluids induced by constant electric fields
Authors: Novotny Vlad J. , Harbour John R.
Published: February 2003

A sudden application of constant electric field across a thin planar cell containing nonaqueous ferrofluid leads to oscillatory, damped electrical and light scattering signals. This surprising phenomenon is associated with the coherent bouncing motion of charged iron oxide particles between cell electrodes. These particles likely undergo charge reversal at the electrodes and their transport is assisted by fluid motion.
Stabilization and optimum biasing of dynamic-single-mode coupled-cavity lasers
Authors: Coldren L. A. , Ebeling K. J. , Swartz R. G. , Burrus C. A.
Published: February 2003

Stabilization and control of coupled-cavity lasers are considered. Constant output power plots on the I1 vs I2 plane determine optimum dc bias points and how the rf modulation should be applied. A double feedback-loop control circuit provides stable, single-mode operation over wide ranges of temperature and power under modulation. Experiments demonstrate ≥24 dB of spurious mode suppression under almost complete on/off high-speed modulation over >15 °C.
Use of a single nonlinear Fabry–Perot étalon as optical logic gates
Authors: Jewell J. L. , Rushford M. C. , Gibbs H. M.
Published: February 2003

The all-optical operation of many logic elements (nor, etc.) on a single passive nonlinear Fabry–Perot etalon is discussed. An experiment using dye-filled etalons verifies the prediction and agrees with a computer simulation. This kind of Fabry–Perot gate should be capable of very high speed operation with minimum energy per cycle.
Statistical properties of a laser driven by colored noise
Authors: Lindenberg Katja , West Bruce J. , Cortes Emilio
Published: February 2003

We obtain an exact analytic solution of the equation of motion for a dye laser with a fluctuating pump parameter of finite correlation time. The exact solution is compared with recent experimental results on the intensity fluctuations of a dye laser. We also obtain a favorable comparison of the experiments to the results obtained from an approximate Fokker–Planck description of the laser.
Ion implantation induced displacement of Ga and As in GaAs
Authors: Bhattacharya R. S.
Published: February 2003

Proton induced x-ray emission has been used, in combination with channeling, to study the displacements of Ga and As atoms in GaAs (100) crystal after ion implantation. O+, S+, and Ar+ ions of various doses were used for implantation. Results indicate a slightly higher displacement of Ga (≲4%) than As atoms for the implantation conditions employed here.
Grain growth in Al alloy conductors as a result of rapid annealing
Authors: Towner Janet M. , van de Ven Evert P. , Hopkins Craig G.
Published: February 2003

Aluminum and aluminum alloy thin films were rapidly annealed using high intensity visible light. Under suitable conditions, substantial grain growth was achieved in the Al-Cu and Al-Si-Cu conductors and this grain growth had a beneficial effect on electromigration. Unfortunately, this growth did not occur uniformily across the wafer. A second phenomenon, which resulted from thermal cycling, was the solid phase reduction of SiO2 by the overlying Al film.
Trap generation and electron detrapping in SiO2 during high-field stressing of metal-oxide-semiconductor structures
Authors: Heyns M. M. , DeKeersmaecker R. F. , Hillen M. W.
Published: February 2003

Direct evidence for electron trap generation during high-field stressing of thermally grown SiO2 layers is obtained using avalanche injection followed by internal photoemission measurements on Al-gate metal-oxide-semiconductor structures. Avalanche injection is used to fill oxide traps with a minimum risk of oxide degradation. It is shown that traps are created near the Si-SiO2 interface of a 39-nm-thick oxide on p-Si stressed in accumulation. After intentional charging the centroid of the additional charge distribution corresponding to the newly created traps is located at 5(±2.5) nm from the Si-SiO2 interface. Any bulk oxide charge is detrapped during a high-field stress. The importance of these findings in relation to breakdown in SiO2 is indicated.
New amorphous silicon nonlinear element for liquid crystal display addressing
Authors: Szydlo N. , Chartier E. , Proust N. , Magariño J.
Published: February 2003

A nonlinear element consisting of two back-to-back platinum/a-Si Schottky diodes made on amorphous silicon prepared by chemical vapor deposition of silane and post-hydrogenation is described. Nonlinearity coefficients α of the I-V characteristics (I=KVα) in the range 7–15 are obtained depending on doping and thickness of the active layer. The high multiplexing capacity (>1000 rows) at the television frame frequency is demonstrated, for the first time, by simulation on a single twisted-nematic cell in series with the device.
Picosecond photoresponse in 3He+ bombarded InP photoconductors
Authors: Downey P. M. , Schwartz B.
Published: February 2003

3He+ bombardment is shown to be an effective means of achieving free-carrier lifetimes as short as 1 ps in Fe-doped InP without compromising the dark resistance of the photoconductor. Autocorrelation measurements demonstrate that these bombarded photoconductors operate as sampling gates with 2-ps sampling apertures and millivolt sensitivity. They exhibit a 10–90% decay time of 30 ps when used as pulse generators; we attribute this behavior to imperfect contacts.
Study of electric field enhanced emission of deep levels using a new emission spectroscopic technique
Authors: Nguyen T. T. , Wang K. L. , Li G. P.
Published: February 2003

A small capture pulse followed by an emission pulse was used to study the carrier emission of defect centers in the presence of electric field. The capture pulse is used to fill a localized group of centers with electrons in n-type semiconductors and a reverse pulse causes these centers to emit electrons at an electric field determined by the reverse-bias pulse. The enhancement of the emission due to the presence of a high electric field can be determined readily from the change of capacitance transients detected using a conventional deep level transient spectroscopy setup. In this technique, a low dc bias is used during the measurement of the capacitance transients and thus results in a high sensitivity of detection. Calculation and experimental results are given for the Ec −0.35 eV center in GaAs.
Impurity trapping, interface structure, and luminescence of GaAs quantum wells grown by molecular beam epitaxy
Authors: Petroff P. M. , Miller R. C. , Gossard A. C. , Wiegmann W.
Published: February 2003

A correlation has been demonstrated between impurity trapping and the interface structure in GaAs quantum well (QW) superlattices and single quantum well structures grown by molecular beam epitaxy (MBE) on (100) GaAs. Using low-temperature cathodoluminescence, photoluminescence, and transmission electron miscroscopy, we have shown that interface roughness in QW superlattices is related to trapped impurities at interfaces. We have observed that impurities originate from either the substrate or from the GaAlAs MBE layers. A new getter smoothing effect associated with QW structures is shown to produce efficient impurity trapping and yield higher quality GaAs QW with atomically smooth interfaces.
Ion beam milling of InP with an Ar/O2-gas mixture
Authors: Katzschner W. , Steckenborn A. , Löffler R. , Grote N.
Published: February 2003

Ion beam etching has been successfully applied to InP using an Ar/O2-gas mixture. Varying angles of beam incidence resulted in different shapes of the etched profiles with the achievement even of undercutting. Good selectivity with respect to Novolak-type photoresists prevails at higher accelerating voltages.
Channeled substrate buried heterostructure InGaAsP/InP laser employing a buried Fe ion implant for current confinement
Authors: Wilt D. P. , Schwartz B. , Tell B. , Beebe E. D. , Nelson R. J.
Published: February 2003

A channeled substrate buried heterostructure InGaAsP/InP laser is demonstrated using a hybrid technique of Fe ion implantation followed by liquid phase epitaxy. A high resistivity region is formed by the implantation and subsequent anneal of Fe into an n-type InP substrate, and this is used to provide a self-aligned current confinement barrier layer. The use of an in situ anneal prior to liquid phase epitaxy minimizes the number of processing steps. Pulsed threshold currents as low as 22 mA have been achieved on devices utilizing broad area metal contacts.
Recrystallization of amorphous gallium arsenide by ion beams
Authors: Sadana D. K. , Choksi H. , Washburn J. , Byrne P. F. , Cheung N. W.
Published: February 2003

An 11-MV arsenic beam was used to amorphize approximately 3.9 μm of GaAs surface layer at liquid nitrogen temperature. It was found that apparently amorphous gallium arsenide can be reconverted to single crystal by subsequent implantation at higher temperature. The recrystallization by the ion beam proceeded simultaneously from the amorphous surface and the deep amorphous/crystalline interface. Growth of dendrites and/or microtwins occurred at the recrystallizing interfaces. From the comparison of the nuclear stopping curve with the damage distribution in cross-sectional transmission electron micrograph, the threshold value for converting crystalline GaAs into amorphous GaAs was measured to be between 2–5×1020 keV cm−3.
Interaction in Cu/Al and Pt/Cu/Al thin films: Competing oxygen effects and preferential reaction between Pt and CuAl alloy
Authors: Chang Chin-An
Published: February 2003

The effects of oxygen on the interactions of the Cu-Al thin-film system are studied using both Cu/Al and Pt/Cu/Al structures. For the Cu/Al structure, oxygen-enhanced outdiffusion of Al and accumulation of Al on the Cu surface are observed. Using the Pt/Cu/Al structure, however, no surface accumulation of Al on Pt is observed; instead, the observed interdiffusion and alloy formation between Cu and Al are both suppressed by oxygen. At increasing temperatures, Al preferentially outdiffuses from the CuAl alloy to form a Pt Al alloy with the top Pt layer. This last process is also suppressed by oxygen, similar to the binary Pt/Al system reported previously. The mechanisms for the competing interactions and ambient effects observed are discussed.
Thermal diffusion of Pt in silicon from PtSi
Authors: Mantovani S. , Nava F. , Nobili C. , Conti M. , Pignatel G.
Published: February 2003

Platinum diffusion in n-type silicon has been measured using various kinds of spectroscopic techniques for deep energy levels. Platinum acts as an acceptor which captures electrons. An energy level of 0.23±0.02 eV was found for the trap. The diffusion profile can be explained, as in the case of gold, with a kick-out mechanism involving silicon self-interstitials. From the model, an activation energy of 5.01 eV for silicon self-interstitial diffusion can be inferred.
Linewidth measurements of a (GaAl)As diode laser with a high reflectivity coating
Authors: Lenth W.
Published: February 2003

The effect of the facet reflectivity on the linewidth of a single-frequency (GaAl)As diode laser has been studied by measuring the linewidth as a function of the laser output power before and after a high reflectivity coating was applied to one facet of the laser. The observed linewidth reduction arising from the increase in the cavity Q agrees with predictions of linewidth theories. The results indicate that the application of high reflectivity coatings can be a practical method for achieving a substantial reduction of the linewidth of (GaAl)As diode lasers.
Illumination stimulated persistent channel depletion at selectively doped Al0.3Ga0.7As/GaAs interface
Authors: Kastalsky A. , Hwang J. C. M.
Published: February 2003

The results of the combined influence of illumination and negative substrate bias on the conductance at Al0.3Ga0.7As/GaAs interface are reported. The observed strong (two to three orders of magnitude) persistent increase in sample resistance is explained with a model of two conducting layers in the heterostructure: (1) an interface channel and (2) a low mobility AlGaAs layer. The simultaneous application of light and substrate bias leads to the generation of electrons and holes, their separation, and their subsequent capture by traps. A counterfield remaining in the sample after the removal of both influences causes a strong persistent channel depetion and an increase of the resistance.
Pulsed laser evaporation of Cd3As2
Authors: Dubowski J. J. , Williams D. F.
Published: February 2003

A pulsed Nd:yttrium aluminum garnet (YAG) laser, power density 4–10×107 W/cm2, was used to prepare thin films of Cd3As2 by evaporation onto room-temperature substrates. The net deposition rate was 105 Å/s. The film microstructure was composed of amorphous agglomerates, 600–2000 Å in size. The films obtained with power density 7–10×107 W/cm2 were stoichiometric and they had electron concentrations of 2.6–10×1018 cm−3 and electron mobilities of 210–520 cm2/Vs at 300 K.
Electron transport in In0.53Ga0.47As/plasma oxide inversion layers
Authors: Liao A. S. H. , Tell B. , Leheny R. F. , Chang T. Y. , Caridi E. A. , Beebe E. , DeWinter J. C.
Published: February 2003

In this letter we report the first direct measurements of low field transport properties for inversion layer electrons in an InGaAs native oxide metal-oxide-semiconductor structure. Our results show that these electrons have a low field mobility which varies from 3000 to 4500 cm2/Vs, compared with 1500 cm2/Vs measured in field-effect transistor structures. We also deduce a surface state density NSS =1.5×1013 cm−2 eV−1 near the conduction-band edge.
Raman spectroscopy of PtSi formation at the Pt/Si(100) interface
Authors: Tsang J. C. , Yokota Y. , Matz R. , Rubloff G.
Published: February 2003

We demonstrate the use of Raman spectroscopy with a multichannel detector to characterize the growth of PtSi on Si(100). The vibrational modes of surface silicide layers as thin as 10 Å and PtSi layers less than 40 Å thick buried under 140 Å of Pt have been observed without the need for any special sample geometry for signal enhancement. The Raman spectra can identify the silicide layer, estimate its thickness, and demonstrate its crystalline quality. This can be done on an arbitrary substrate, in air and without any special sample preparation.
High quantum efficiency amorphous silicon photodetectors with picosecond response times
Authors: Johnson A. M. , Glass A. M. , Olson D. H. , Simpson W. M. , Harbison J. P.
Published: February 2003

Amorphous silicon Schottky barrier photodetectors with internal quantum efficiencies of 36% and sampling oscilloscope limited response times of 40 ps (full width at half-maximum) have been fabricated. Utilizing ultrathin films of rf glow discharge deposited hydrogenated amorphous silicon, carrier sweep-out was achieved in a new microstrip transmission line structure. The performance of these devices, for picosecond pulse detection, is now comparable to that of crystalline semiconductor detectors.
New model for slow current drift in InP metal-insulator-semiconductor field-effect transistors
Authors: Goodnick S. M. , Hwang T. , Wilmsen C. W.
Published: February 2003

The drift in channel current of SiO2/InP metal-insulator-semiconductor field-effect transistors has been calculated using a model in which electrons thermionically tunnel to a conducting layer of In2O3 within the native oxide at the interface. Calculations based on this model using reasonable values for the interface parameters are in good agreement with experimental data. The model differs from previous drift models in that trapping occurs between bulklike materials and not through discrete trap levels and is based on physical evidence for the structure of the SiO2/InP interface.
Residual defects following rapid thermal annealing of shallow boron and boron fluoride implants into preamorphized silicon
Authors: Carter C. , Maszara W. , Sadana D. K. , Rozgonyi G. A. , Liu J. , Wortman J.
Published: February 2003

Shallow BF2 and B implants (42 keV, 2×1015 cm−2) were conducted at either liquid nitrogen or room temperature into deeply preamorphized (100) Si. Cross-sectional transmission electron microscopy revealed that subsequent rapid thermal annealing (RTA) of the room-temperature implanted BF2 sample in the temperature range 950–1150 °C for 10 s created three classes of secondary defects at three different depth levels. The depths corresponded closely to the projected range of the BF2 implant, the deep amorphous/crystalline interface, and the region immediately below the interface. In contrast, RTA of preamorphized Si with or without the shallow B implant both resulted in a high perfection surface region with secondary defects only in the region below the deep amorphous/crystalline interface. A phenomenological model for nucleation of the separate layers of defects is presented.
I
V curves of long annular Josephson junctions
Authors: Davidson A. , Pedersen N. F.
Published: February 2003

I V curves of long annular Josephson junctions (circumference much larger than the Josephson penetration depth) have been investigated numerically. It is concluded that an experiment on such a system is preferable to the usual linear geometries and will allow a study both of the undisturbed motion of a fluxon, and the fluxon-antifluxon collision process. The simulations show that the fluxon-antifluxon collisions generate long wavelength plasma oscillations which may give rise to fine structure in the IV curves.
Influence of as-deposited film structure on 〈100〉 texture in laser-recrystallized silicon on fused quartz
Authors: Kimura Masakazu , Egami Koji
Published: February 2003

A strong 〈100〉 texture has been achieved in cw neodymium:yttrium aluminum garnet laser recrystallization of the 700 °C low pressure chemical vapor deposited (LPCVD) polycrystalline silicon films which exhibit 〈100〉 preferred orientation. When 〈110〉 texture is dominant in as-deposited films, the 〈100〉 texture is not so strong as in the 700 °C LPCVD films. The dependence of the 〈100〉 texture on as-deposited film structure implies that the 〈100〉 grain growth occurs under such a melting condition as the initial film structure is partially maintained.
Continuous operation of monolithic dynamic-single-mode coupled-cavity lasers
Authors: Coldren L. A. , Ebeling K. J. , Rentschler J. A. , Burrus C. A. , Wilt D. P.
Published: February 2003

The first cw monolithic two-section lasers were fabricated using reactive-ion-etched grooves in buried-crescent wafers. Tunable single-mode selection with spurious mode levels down ∼20 dB was demonstrated under modulation.
High efficiency coupling to the overcoated surface plasmon mode in the far infrared
Authors: Seymour R. J. , Krupczak J. J. , Stegeman G. I.
Published: February 2003

Trapezoidal gratings, both with and without thin dielectric overcoatings, have been used to couple up to 70% of a 119-μm laser beam into surface plasmons on a metal surface. The results indicate significant grating induced shifts in the dispersion relations.
CO2 laser using electrochemical transformation of organic compounds
Authors: Midorikawa K. , Tashiro H. , Namba S.
Published: February 2003

A novel CO2 laser using electrochemical transformation of organic compounds (ECTO) has been developed. cw CO2 laser action was obtained by applying an electric discharge to the air, which contained organic vapors such as alcohols and benzene derivatives. The CO2 molecules produced by the chemical reaction in the laser tube and the N2 molecules contained in the air were excited by the discharge. The ECTO CO2 laser produced an output power of 7 W, which was comparable to the power obtained from a conventional CO2 laser gas mixture.
Optical bistability at the band gap in InAs
Authors: Poole C. D. , Garmire E.
Published: February 2003

Observation of optical bistability at the band gap in InAs is reported. Clear hysteresis was seen in the reflected signal from a Fabry–Perot etalon consisting of polished n-type InAs with silver deposited on the back surface. By using the 3.096-μm line of an HF laser, which matches the band gap at 77 K, bistable switching was achieved with power levels as low as 3 mW (peak intensity 75 W/cm2).
Phase locking of adjacent channel leaky waveguide CO2 lasers
Authors: Youmans D. G.
Published: February 2003

Phase locking has been achieved between two adjacent waveguide CO2 lasers separated by a thin plate of ZnSe. Radiation leakage from one waveguide to the other through the ZnSe causes the phase locking, and stationary interference fringes demonstrate the relative phase stability. Both waveguide lasers are excited by dc discharges and operate on one of several P or R transitions in the 10.4-μm band. Phase locking occurs whenever both waveguides are on the same transition. An n by m array of such phase-locked lasers has the potential of nearly an (n×m)2 increase in the peak of the lasers’ far-field irradiance distribution.
Parametric generation of tunable picosecond pulses in the medium infrared using AgGaS2 crystals
Authors: Elsaesser T. , Seilmeier A. , Kaiser W. , Koidl P. , Brandt G.
Published: February 2003

Infrared pulses were generated over the range from 1.2 to 10 μm in a single path system consisting of two AgGaS2 crystals. A high photon conversion efficiency between 10−1 and 10−3 was found depending upon the emission frequency. A bandwidth of approximately 10 cm−1 for idler pulses between 6 and 10 μm was observed. With a Nd:yttrium aluminum garnet laser pump of 20-ps pulse duration one observes parametric pulses of 8 ps.
Absolutely uniform illumination of laser fusion pellets
Authors: Schmitt Andrew J.
Published: February 2003

Absolutely uniform illumination of spherical laser fusion pellets is possible when the energy deposition from a single beam is given by a simple cos2 θ distribution. Conditions can be derived for which the laser beam targeting angles allow this absolute illumination uniformity. Configurations based upon the cube and higher order Platonic solids satisfy the constraints, as well as an infinite class of other less symmetric configurations.
Electric field induced morphological changes in nylon 11
Authors: Jacobs E. W. , Hicks J. C.
Published: February 2003

Electric field induced changes in the x-ray diffraction pattern of nylon 11 films containing a mixture of the alpha and gamma crystal phases are presented. These changes indicate an orientation of crystallites such that dipoles are aligned in the direction of the poling field. Correlation between this crystal orientation and piezoelectric activity was observed.
Gap states in silicon nitride
Authors: Robertson John , Powell Martin J.
Published: February 2003

The energy levels of defect states in amorphous silicon nitride have been calculated and the results are used to identify the nature of trap states responsible for charge trapping during transport and the charge storage leading to memory action. We argue that the Si dangling bond is the memory trap in chemical vapor deposited memory devices and is also the center in plasma-deposited nitride responsible for hopping at low electric fields and for charge-trapping instabilities in amorphous silicon-silicon nitride thin-film transistors.
Determination of SiO2 trapped charge distribution by capacitance-voltage analysis of undoped polycrystalline silicon-oxide-silicon capacitors
Authors: Nissan-Cohen Y. , Shappir J. , Frohman-Bentchkowsky D.
Published: February 2003

Capacitance measurements on undoped polycrystalline silicon gate capacitors are used for oxide trapping characterization. In this structure, a field-effect modulation on both interfaces is observed in a single C-V plot. A variation in the insulator charge state is detected by its effect on both interfaces. The main advantage of this method is that both trapped charge magnitude and centroid are obtained by a single measurement with a minimal disturbance of the charge distribution. The method is demonstrated on thin oxide capacitors subjected to negative or positive charge trapping. The induced positive and negative charge magnitude and location dependence on the injection conditions are measured and analyzed.
Open-tube isothermal vapor phase epitaxy of Hg1−xCdxTe on CdTe
Authors: Shin S. H. , Pasko J. G.
Published: February 2003

Device-quality Hg1−xCdxTe (0.2≤x≤0.35) epitaxial layers have been grown on CdTe substrates by open-tube isothermal vapor phase epitaxy (ISOVPE). The surface morphology of the layers is mirrorlike, and the Hall data are comparable to those for HgCdTe grown by liquid phase epitaxy (LPE). Photovoltaic devices with a cutoff wavelength of 4.1 μm at 77 K were fabricated on an ISOVPE HgCdTe epilayer. Their performance is comparable with those that we have obtained for such devices fabricated on LPE HgCdTe epilayers.
Impurity-induced disordering of single well AlxGa1−xAs-GaAs quantum well heterostructures
Authors: Meehan K. , Brown J. M. , Camras M. D. , Holonyak N. , Burnham R. D. , Paoli T. L. , Streifer W.
Published: February 2003

Transmission electron microscopy and photoluminescence data are used to show that a single GaAs quantum well (Lz ≊70 Å) confined by Alx′Ga1−x′As (x′∼0.3) layers can, via low-temperature (600 °C) Zn diffusion, be interdiffused (‘‘absorbed’’) into the confining layers (impurity-assisted Al-Ga interdiffusion) and be shifted to higher gap (x=0→x′∼0.3) without damaging the crystal or ruining its capability to operate as a continuous 300-K low threshold photopumped laser.
Raman scattering spectrum analyses for fluorine-doped silica optical fibers
Authors: Noguchi Kazuhiro , Murakami Yasuji , Uesugi Naoshi , Ishihara Koushi
Published: February 2003

Raman scattering spectra for fluorine-doped silica fibers are measured. A Raman scattering peak, assigned to be the Si–F bond in the fibers, is observed at a wave number of 930 cm−1. Heat tests in a hydrogen gas atmosphere are carried out. The result shows that the fiber loss due to the hydroxyl group, which is produced by the heat test, decreases by fluorine doping. These phenomena show that the Si–O–Si bond defects are filled with doped fluorine atoms, and oxygen atoms positioned at the defects are exchanged by the fluorine atoms.
Novel x-ray backlighting method for measuring areal densities of Rayleigh–Taylor unstable, ablatively driven targets
Authors: Grun J. , Kacenjar S.
Published: February 2003

We describe a face-on x-ray backlighting method that does not require a dedicated laser beam and a separate x-ray source. This method is used to measure the lateral mass transfer characteristic of the Rayleigh–Taylor instability in ablatively accelerated, laser driven targets.
Electron beam cutting in amorphous alumina sheets
Authors: Mochel M. E. , Eades J. A. , Metzger M. , Meyer J. I. , Mochel J. M.
Published: February 2003

We have found that nanometer diameter holes and slots can be cut in thin sheets of amorphous alumina using an intense electron beam. The holes, formed by a nonthermal process, are uniform in diameter, are surrounded by metallic aluminum, and can penetrate a 100-nm sheet in a few seconds. The amorphous alumina sheets are formed by anodization of electropolished high purity aluminum. The electron beam cutting seems very similar to the process reported in the metal β-aluminas. Since uniform, stable, and easily handled sheets of amorphous alumina can be fabricated and electron beam cut, this process is now practical for nanolithography as well as many other applications.
Spectroscopic ellipsometric and He backscattering analyses of crystalline Si-SiO2 mixtures grown by molecular beam epitaxy
Authors: Maloney T. J. , Aspnes D. E. , Arwin H. , Sigmon T. W.
Published: February 2003

Single-crystal layers of silicon oxide (SiOz) grown on crystalline Si (c-Si) substrates by molecular beam epitaxy have been analyzed by spectroscopic ellipsometry (SE) and 2.2-MeV He backscattering. The optical properties of SiOz clearly indicate that it is a phase-separated mixture of c-Si and SiO2. Backscattering data combined with the SE results show that SiOz consists of 43 vol. % c-Si, 43 vol. % voids, and 14 vol. % SiO2. The results suggest that registry is preserved by the c-Si inclusions, which also act as nucleation sites for subsequently grown epitaxial c-Si films. The tendency of SiOz to oxidize rapidly at high temperature suggests that it may be useful for dielectrically isolating epitaxial c-Si films.
Spatially resolved observation of carrier leakage in 1.3-μm In1−xGaxAsyP1−y lasers
Authors: Chen Liang-Hui , Mattos J. C. V. , Prince F. C. , Patel N. B.
Published: February 2003

We report spatially resolved observation of carrier leakage over heterobarriers between a thin InGaAsP active layer (eg∼0.9 eV) and symmetric InGaAsP confining layers (Eg∼1.28 eV), in a double-heterostructure laser. Peaks of short wavelength emission of about 1 μm were found to originate from the confining layers indicating that significant carrier leakage, not only of electrons but also of holes can occur. Additional experimental observations suggest that the surprising observation of significant hole leakage may be due to the existence of hot holes created by Auger and/or intervalence band absorption processes.
Measurements of intensity fluctuations of an InGaAsP external cavity laser
Authors: Liu Pao-Lo , Eisenstein G. , Tucker R. S. , Kaminow I. P.
Published: February 2003

We have measured the statistical distributions of intensity fluctuations in an external cavity semiconductor laser. The cavity was formed by coupling a 6.8-cm-long multimode fiber to an antireflection coated, 10-μm-wide InGaAsP ridge-waveguide laser. The fluctuations of the intensity of the laser are small when the cavity is adjusted for single-longitudinal-mode operation.
Formation of GaAsP by ion implantation and annealing
Authors: Aina O. , Pande K. P.
Published: February 2003

Surface layers of GaAsP have been formed by a high dose, shallow implantation of phosphorus into GaAs. Al Schottky contacts on these layers have a higher barrier height (1.04 eV) than similar contacts on unimplanted GaAs. Electron channeling patterns in the scanning electron microscope, infrared absorption measurements, and Auger electron spectroscopy show that a single crystal with a surface composition of GaAs0.83P0.17 is formed.
Electron energy distributions using the time-resolved free-bound spectra from coronal plasmas
Authors: Matthews D. L. , Kauffman R. L. , Kilkenny J. D. , Lee R. W.
Published: February 2003

The first subnanosecond, time-resolved, and spatially localized recombination continuum measurements are reported. The possibility of a non-Maxwellian velocity distribution is deduced from the shape of the recombination spectrum that is observed during the time when the plasma is being created by the laser. The cooling rate of the plasma is derived for later times, when no laser heating is present.
High efficiency inversion layer solar cells based on ionizing radiation-induced surface inversion
Authors: Okuyama Yoshi , Ma T-P.
Published: February 2003

High efficiency inversion layer solar cells have been fabricated using ionizing radiation to produce the inversion layer. A highly conductive transparent film of In2O3 covers the entire cell, which serves as the collecting electrode. A total area efficiency of 16.0% under AM1 illumination (100 mW/cm2) with corresponding open-circuit voltage, short-circuit current density, and fill factor of 623 mV, 32.7 mA/cm2, and 78.4% respectively, has been achieved without antireflection coating. The cell is stable at a temperature as high as 250 °C for as long as the test has been going on (several months so far). The fabrication procedure and radiation treatment are described, and some of the test results are presented.
A new Q switching method by intracavity phase modulation in a semiconductor laser
Authors: Kitayama Ken-ichi , Wang Shyh
Published: February 2003

A new Q switching method for a semiconductor laser is proposed that uses an intracavity phase modulation due to the electro-optic effect. It consists of an amplifier and two phase modulators driven by a microwave signal in a branching waveguide structure. It is predicted that under Q switching a pulse width of less than 100 ps with an intense peak power of a few watts is obtainable even with dc injection current slightly larger than the threshold by applying a microwave reverse bias voltage to the phase modulators.
Threshold temperature dependence of subnanosecond optically excited 1.3-μm InGaAsP lasers
Authors: Martinez O. E. , Heritage J. P. , Miller B. I. , Dutta N. K. , Nelson R. J.
Published: February 2003

We report the first measurement of the temperature dependence of the relative threshold carrier density, Nth, in InGaAsP-InP lasers. The characteristic temperature T′0, defined by 1/T0 ≡d ln Nth/dT, which is independent of nonradiative recombination mechanisms, is determined by transient pumping of a simple double heterostructure laser with optical pulses short (≂100 ps) compared to the carrier lifetime (2–3 ns). A single T′0 as large as 120 K describes an exponential threshold dependence on temperature over a wide temperature range (160–370 K). Comparison with steady state (300 ns) excitation of the same samples shows that nonradiative recombination is responsible for the commonly observed injection laser break from a low-temperature T0≂100 K to the poorer room-temperature T0≂65 K. The measured T0 is smaller than a previously calculated value of approximately 200 K.
10-MHz single photon counting at 1.3 μm
Authors: Levine B. F. , Bethea C. G.
Published: February 2003

We have demonstrated single photon detection (for λ=1.3 μm) at a counting rate of 10 MHz. This is the highest photon counting rate ever achieved. We find that the quantum efficiency η is a weak function of the dark count rate of rd, namely, η∝(rd)0.2. These results are encouraging for possible quantum limited lightwave receiver applications.