bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relaxation of Mismatched InxAl1−xAs/InP Heterostructures
Authors: Bennett Brian R. , del Alamo Jesús A. 
Published: March 2011

ABSTRACTWe have investigated the relaxation of intentionally mismatched layers of InxAl1−x-As on InP. The layers were grown by MBE and characterized by double-crystal x-ray diffraction (DCXRD) and variable azimuthal angle ellipsometry. Measurements of DCXRD epitaxial layer peak width show high crystalline quality for layers up to five times the Matthews-Blakeslee critical layer thickness. For thicker layers, relaxation occurs with a change in crystal symmetry from tetragonal to orthorhombic. We attribute this to an asymmetry in misfit dislocation density. Ellipsometry reveals optical anisotropy for mismatched layers in compression, but not in tension.
A Grazing Incidence X-Ray Reflectometer for Rapid Nondestructive Characterization of Thin Films and Interfaces
Authors: Loxley N. , Monteiro A. , Cooke M. L. , Bowen D. K. , Tanner B. K. 
Published: March 2011

ABSTRACTWe describe a novel instrument dedicated to making rapid angular-dispersive grazing incidence X-ray reflectivity measurements. A novel, automatic, optical technique for rapid specimen alignment, is incorporated into the control software. We discuss the information content of diffuse scattering data collected in non-standard modes. Examples of data are presented showing the application to the characterization of semiconductors and metal multilayers. The technique is shown to be particularly powerful for measurement of the thickness of epitaxial films of AlGaAs on GaAs less than 50 nm thick and where high resolution X-ray diffraction becomes impracticable. We demonstrate that, as the method is insensitive to dislocation density, high quality data can be taken rapidly from heavily relaxed multilayers. Minimum criteria for adequate information content in the data are explored and the effect of specimen curvature is examined.
Carrier Mobility and Active Layer Sheet Measurements of Compound Semiconductors
Authors: Denenberg David , Blew Austin 
Published: March 2011

ABSTRACTThis paper describes a compact production line microwave (approx. 10 GHZ) active layer sheet resistivity carrier mobility measurement instrument based on the invention from IBM Watson Labs by Dr. Norman Bras lau. [1]The Measurement techniques and compound semiconductor wafer measurements will be described.
Growth of GaAs, InxGa1−xAs, and AlxGa1−xAs on GaAs (111)B Substrates by Molecular Beam Epitaxy
Authors: Yang K. , Schowalter L. J. , Laurich B. K. , Smith D. L. 
Published: March 2011

ABSTRACTWe have studied the growth of GaAs, InxGa1−xAs, and AlxGa1−xAs on on-axis GaAs (111)B substrates by MBE. RHEED patterns are used to identify different growth conditions. Using the optimized growth parameters, GaAs and Al0.3Ga0.7As films with surface defect densities (observed under an optical microscope) of less than 50 cm−2 were routinely achieved. No significant differences in surface morphology and carrier concentration were found between As4 and As2 if their mass fluxes are the same. A Hall mobility of 30,000 cm2V−1s−1 at 77 K was obtained for a GaAs film with a free electron concentration of 2×1015cm−3.
Low Temperature Growth of GaAs and AlGaAs by Mombe
Authors: Abernathy C. R. , Bohling D. A. , Jones A. C. 
Published: March 2011

ABSTRACTWe have examined various methods of overcoming the problems of low growth efficiency and high carbon uptake which occur when GaAs is grown at low temperatures by Metal Organic Molecular Beam Epitaxy (MOMBE). We have found that removal of the carbon through conventional means such as precracking or interaction with hydrogen is not effective in enhancing the carbon removal process. In fact, the use of a hydrogen plasma during growth actually increases the carbon background due to a reduction in the surface V/III ratio. Greater success is obtained when alternative precursors are used as replacements for AsH3 and triethylgallium (TEG). Tris-dimethylaminoarsenic (DMAAs) offers reduced carbon uptake through formation of amine compounds while tri-isobutylgallium (TTBG) shows better efficiency and less carbon than TEG at low growth temperature.
Wet and Dry Etching of InGaP
Authors: Lothian J. R. , Kuo J. M. , Pearton S. J. , Ren F. 
Published: March 2011

ABSTRACTThe wet chemical etching rates of InGaP in H3 PO4:HCL:H2O mixtures have been systematically measured as a function of etch formulation and are most rapid (-1 μm · min−1) for high HCl compositions. The etch rate, R, in a 1:1:1 mixture is thermally activated of the form R ∝ e−Ea/kT, where Ea = 11.25 kCal · mole−1. This is consistent with the etching being reaction-limited at the surface. This etch mixture is selective for InGaP over GaAs. For chlorine-based dry etch mixtures (PCl3 /Ar or CCl2 F2 /Ar) the etching rate of InGaP increases linearly with DC self-bias on the sample, whereas CH4/H2-based mixtures produce slower etch rates. Selectivities of ≥500 for etching GaAs over InGaP are obtained under low bias conditions with PCl3/Ar, but the surface morphologies of InGaP are rough. Both CCl2F2/Ar and CH4/H2/Ar mixtures produce smooth surface morphologies and good (>10) selectivities for etching GaAs over InGaP.
Anisotropic Reactive Ion Etching of Submicron W Features In CF4 or SF6 Plasmas
Authors: Fullowan T. R. , Ren F. , Pearton S. J. , Mahoney G. E. , Kostelak R. L. 
Published: March 2011

ABSTRACTAnisotropie RIE etching of Tungsten (W) in a low voltage CF4 or SF6 plasma while achieving features as small as 0.50 μm is demonstrated using Titanium (Ti) as an etch mask. For reasons of reliability and tolerance to high temperature processing techniques, W can be a desirable contact metal in microelectronics fabrication. Due to its high melting point (3400°C) it is not practical to evaporate W contacts using conventional liftoff photolithography methods. Therefore pattern transfer of sputtered W must be performed by plasma etching using some type of mask. In III-V materials systems, a Fluorine based plasma is desirable due to its high selectivity for W over semiconductor materials. The problem is that when using conventional photoresist masks, W does not etch anisotropically. Therefore critical feature dimensions (which are sub-micron for FET gates) and vertical profiles cannot be successfully transferred to the underlying W. However by using a Ti mask during the CF4 or SF6 plasma etch, TiF4 is produced on the sidewalls of the W inhibiting any horizontal etch. The Ti mask can be removed selectively after etching of the W is complete. Using a Ti mask to etch W ensures excellent pattern transfer of device dimensions even at very low bias voltage.
Low Damage Magnetron Reactive Ion Etching of GaAs
Authors: Mclane G. , Meyyappan M. , Cole M. W. , Lee H. S. , Lareau R. , Namaroff M. , Sasserath J. 
Published: March 2011

ABSTRACTMagnetron reactive ion etching is an attractive alternative to reactive ion etching since it has the potential for producing minimal surface damage while still retaining the advantages of reactive ion etching. We report here the results of a study of GaAs magnetron ion etching using Freon-12 and silicon tetrachloride etch gases. Differences are found in etch profiles and surface region characteristics of GaAs samples etched by the two gases. The relevant mechanisms are discussed.
The Use of Tertiarybutylphosphine and Tertiarybutylarsine for the Metalorganic Molecular Beam Epitaxial Growth of Resonant Tunneung Devices
Authors: Beam E. A. , Seabaugh A. C. 
Published: March 2011

ABSTRACTWe report on the use of thermally-cracked tertiarybutylphosphine (TBP) and tertiarybutylarsine (TBA) with elemental Ga, In, and Al sources for the MOMBE growth of InP-based resonant tunneling diode (RTD) and resonant tunneling bipolar transistor (RTBT) structures. We have systematically examined the effects of growth conditions and heterostructure modifications on the InP/lnGaAs RTD including the use of pseudomorphic (InGa)P barriers and, in addition, explored for the first time, InP quantum well RTDs using both AlAs and InGaP barriers. Cross-sectional transmission electron microscopy has been used to correlate the structural quality with the electrical characteristics for both lattice-matched and pseudomorphic layers composed of InAs, AlAs, and InGaP. We also demonstrate the first use of mixed InP/lnGaAs and AlAs/lnGaAs heterojunctions in the RTBT. These transistors exhibit room temperature negative transconductance and a peak-to-valley current ratio of 35, the highest yet observed In the RTBT.
Multichamber Rie Processing for Ingaasp Ridge Waveguide Laser Arrays
Authors: Rothman Mark A. , Thompson John A. , Armiento Craig A. 
Published: March 2011

ABSTRACTThe fabrication of devices based on III-V materials often requires a number of different reactive ion etching (RIE) processes that must be implemented sequentially. These processes are typically carried out in different RIE systems to avoid cross contamination. In this paper, we describe a multichamber RIE system configured to provide several sequential etch processes required for the fabrication of optoelectronic devices. This system has been used to fabricate InGaAsP/lnP ridge waveguide laser arrays with etched mechanical features that enable passive alignment of the lasers with single-mode fibers. Laser arrays with threshold currents as low as 20 mA have been processed with a high degree of uniformity. This system has also been used to develop a laser facet etch process based on CH4/H2/Ar chemistry. This process has been used to fabricate lasers with monolithically integrated rear facet monitors. These etched facet lasers have threshold currents comparable to lasers with both facets cleaved.
An Etch-Back Planarization Process Using A Sacrificial Polymide Layer
Authors: Lothian J. R. , Fullowan T. R. 
Published: March 2011

ABSTRACTAn etch-back polymide planarization process for the emitter contact of AlGaAs/GaAs HBTs using PC-1500 is presented. The degree of surface topography has a major impact on the yield in HBT fabrication. A planarization process using a spin-on sacrificial layer to produce a planar interlevel dielectric layer would be very beneficial in allowing thicker and more uniform emitter contacts therefore enhancing the yield and current handling capability. The PC-1500 polymer flows at 200°C and provides a much better planarity than regular photoresist. For patterns from -3 μm to 250 this polymer can achieve 80% to 92% planarity. The wafers were etched in a parallel plate, single wafer reactive ion-etching system with a mixture of oxygen and Freon-14. The etch rate of this polymer increased with the oxygen content of the discharge then became fairly constant at high O2 concentrations while the etch rate of the underlying dielectric film (SiN) was proportional to the Freon 14 content. This new polymer shows little loading effect. A 1:1 etch rate ratio of SiN to PC-1500 was established for good planarity.
Reactive Ion Etching of TaSix in a CF4-O2 Discharge
Authors: Chen C. P. , Din K. S. , Huang F. S. 
Published: March 2011

ABSTRACTIn the self-alignment technology for GaAs MESFET, the pattern technique for refractory suicide gate is needed. Reactive ion etching (RIE) of TaSix on GaAs has been performed in a mixture of CF4 and O2 Etching properties have been studied as function of oxygen percentage, total pressure and power. The samples were then examined in Scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) to understand the surface morphology and constitution. It is found that the etch rate of TaSixincreased with increasing oxygen percentage initially, reached a maximum value near 10∼15% O2, then started to decrease with increasing oxygen at applied power 100 watt, pressure 50 mtorr, and total gas flow 40 seem. This etch rate also increases with RF power and total pressure in CF4 + O2 15% gas at gas flow rate 40 sccm. For GaAs etching, the rate is independent of oxygen percentage. This etch rate of GaAs also increases with power, but decreases with total pressure. Meanwhile, the SEM micrograph shows no undercut for sample after RIE at the applied power 140 watt with the pressure of 20 mtorr.
Use of Pt Gate Metallization to Reduce Gate Leakage Current in GaAs MESFETs
Authors: Ren F. , Emerson A. B. , Pearton S. J. , Hobson W. S. , Fullowan T. R. , Lothian J. 
Published: March 2011

ABSTRACTThe use of wet-chemical removal of native oxide in a sealed nitrogen ambient prior to deposition of metal on GaAs is shown to be an effective method of engineering the Schottky barrier height of the metal contacts. Due to its higher metal work function, a barrier height of 0.98 eV for Pt on n-type GaAs is demonstrated. This is considerably higher than the barrier height of conventionally processed TiPtAu contacts (0.78 eV). MESFETs fabricated using PtAu bilayer contacts show reverse currents an order of magnitude lower than TiPtAu contacted companion devices, higher reverse breakdown voltages and much lower gate leakage. Utilizing this technology of oxide removal and the PtAu bilayer contact provides a much simpler method of enhancing the barrier height on n-type GaAs than other techniques such as counter-doping the near-surface or inserting an interfacial layer.
Sintered Ohmic Contacts to GaAs
Authors: Cibuzar Gregory T. 
Published: March 2011

ABSTRACTThe formation of reliable low resistance ohmic contacts to GaAs and other III-IV compound semiconductors is essential for useful device and circuit fabrication. We have modified the standard AuGe ohmic contact process by using rapid thermal annealing at temperatures less than the AuGe eutectic temperature to form contacts based on sintering rather than alloying. Compared with alloyed contacts, sintered contacts have similar electrical performance, superior morphology, and improved reliability. Results from secondary mass spectroscopy analysis of sintered and alloyed contacts will be discussed.
Quasi-Schottky Diodes on (n)In.53Ga.47as with Barrier Heights of 0.6 eV
Authors: Marso M. , Kordoš P. , Meyer R. , Lüth H. 
Published: March 2011

ABSTRACTThe modification and control of the Schottky barrier height on (n)InGaAs is an important tool at the device preparation as the barrier height is very low, øB° = 0.2 eV. We report about the Schottky barrier enhancement on (n)InGaAs by thin fully depleted surface layers of high doped (p+)InGaAs. Structures with different thicknesses of (p+)InGaAs in the range from 8 to 80 nm were grown by LP MOVPE technique and quasi-Schottky diodes with different contact areas were prepared using titanium as a barrier metal. I-V and I-T characteristics were measured and analysed to obtain basic parameters of prepared diodes, i. e. ideality factor n, effective barrier height øB, series resistance Rgand reverse current density JR (1V). The barrier height enhancement increases with the thickness of the (p+)-layer. Effective barrier heights of øB>0.6 eV, i.e. higher than reported until now, can be obtained with the surface layers of (p+)InGaAs with thicknesses exceeding 25 nm.
Temperature Dependent Schottky Contacts to InP and GaAs
Authors: Shi Z. Q. , Wallace R. L. , Anderson W. A. 
Published: March 2011

ABSTRACTThe barrier height of a Pd/n-InP diode was found to be increased from 0.48 to 0.96eV with the substrate temperature decreased from 300 to 77K during metal deposition. The leakage current density was reduced by more than six order of magnitude. It is obvious that the interface Fermi-level position lies well outside the variance associated with Fermi-level pinning. The barrier height for the Au/n-GaAs diode was found to be increased by about 0.25 eV with low temperature deposition and the leakage current reduced by more than five orders of magnitude. The mechanism responsible for the ultrahigh barrier height obtained at low substrate temperature was investigated by Raman spectroscopy, current voltage temperature measurement, deep level transient spectroscopy, and electroreflectance technique. The metal-insulator-semiconductor (MIS)-like structure formed at low substrate temperature and the reduction of interface state density may be the main reason for the dramatic enhancement of Schottky barrier height.
Stable Schottky Contacts to n-Type GaAs Produced by Ge Rich Co-Ge Metalization
Authors: Koltin E. , Eizenberg M. 
Published: March 2011

ABSTRACTInterfacial reactions between thin films of cobalt and germanium on (001) oriented GaAs substrates were studied in two configurations, Co/Ge/GaAs and Ge/Co/GaAs, with emphasis on Ge rich stoichiometries. It was found that at low temperatures, 250≤T<350δC, cobalt reacted with germanium to form intermetallie compounds which depended on the Co/Ge atomic ratio, while the inner interface with the GaAs substrate remained intact. At higher temperatures (up to 600δC) a limited reaction with the GaAs substrate was detected. This reaction was contained for both configurations near the interface with the substrate, and did not develop with temperature. The extent of reaction decreased with the decrease in the Co:Ge atomic ratio. Contacts produced in these systems were rectifying with a nearly ideal thermionic emission behavior.
A Novel GaAs Bipolar Transistor Structure with GaInP-Hole Injection Blocking Barrier
Authors: Pletschen W. , Bachem K. H. , Lauterbach T. 
Published: March 2011

ABSTRACTGaAs bipolar transistors of different emitter types have been fabricated from MOCVD grown lattice matched Ga0.5In0.5 P/GaAs layer structures using carbon for heavy base doping (p=2×1019 cm−3). Besides conventional heterojunction bipolar transistors we also investigated tunneling emitter bipolar transistors having 2 and 5 nm thin GalnP layers between emitter and base, which act as a hole repelling potential barrier in the valence band. Current gains up to 115 have been obtained at collector current densities of 104 A/cm2 even for this heavy base doping. All devices show an almost ideal output characteristics with large Early voltage and small offset voltage. From the temperature dependence of the collector current a small effective conduction band barrier at the heterointerface is determined which hardly affects electron injection into the base.
High-Performance Structure of Light-Emitting Diode for GaAs on Si Tetsuroh Minemura
Authors: Asano Junko , Yazawa Yoshiaki 
Published: March 2011

ABSTRACTThe Light-emitting diode (LED) structures have been investigated to realize high-performance LEDs on Si substrates. The light intensity of the LEDs with p-GaAs / n-GaAs / Si structures, which was effected from thickness of the p-GaAs layer, was only about 55% of the homoepitaxialLED. The light intensity of the LED with an n-GaAs/p-GaAs/Si structure, however, was about four times stronger than those of p-GaAs/n-GaAs/Si structures. After continuous operation for two hours, the intensity still kept much stronger than those of the LEDs with p-GaAs / n-GaAs / Si structures, although it decreased to 15% of the homoepitaxial LED.
Integrated Distributed Feedback Laser and Optical Amplifier
Authors: Dutta N. K. , Lopata J. , Logan R. , Tanbun-Ek T. 
Published: March 2011

ABSTRACTThe fabrication and performance characteristics of an integrated distributed feedback (DFB) laser and optical amplifier structure are described. The structure utilizes semi-insulating Fe doped InP layers for current confinement to the active region, electrical isolation between the two sections and for lateral index guiding. The amplified output has a slope of 1 mW/mA of laser current with the amplifier biased at 150 mA which is a factor of 5 larger than that for a typical laser. The laser emits near 1.55 μm and the spectral width under modulation of the amplified output is considerably smaller than that for a DFB laser for the same on/off ratio.
The Effect of Rapid Thermal Annealing on the Electrical and Material Characteristics of Planar Doped and Uniformly Doped GaAs/AiGaAs/InGaAs Pseudomorphic HEMT Structures
Authors: Kazior T. E. , Brierley S. K. 
Published: March 2011

ABSTRACTMBE grown GaAs/Al0.25Ga0.75As/In0.85Ga0.85 As structures were subjected to SiNx capped rapid thermal annealing and their electrical and material properties were characterized by Hall measurements and photoluminescence (PL). Low temperature (5°K) PL spectra from undoped structures annealed up to 900°C indicated negligible intermixing at the AIGaAs/lnGaAs interface. For planar doped structures (Nd≈5×1012/cm2) the Hall mobility began to decrease at anneal temperatures as low as 800°C with significant degradation observed for annealing temperatures at 850°C. This data is supported by PL spectra which indicate no significant change for samples annealed at 800°C. For the samples annealed at ≥ 850°C a large increase in the full width at half maximum of the transitions from the electron sub-bands of the InGaAs quantum well were observed, suggesting that the change in electrical characteristics is primarily due to diffusion of the Si doping pulse. In contrast. Hall measurement of uniformly doped structures reveal only small decreases in mobility and no significant change in sheet concentration for anneal temperatures up to 900°C and doping levels up to 2.5×1018/cm3. PL spectra reveal no structural changes.
P-Type Quantum Well Infrared Photodetectors Grown by OMVPE
Authors: Hobson W. S. , Zussman A. , De Jong J. , Levine B. F. 
Published: March 2011

ABSTRACTWe report on the growth and fabrication of p-doped long wavelength GaAs/AlxGa1−x As quantum well infrared photodetectors (QWIP) grown by organometallic vapor phase epitaxy. The operation of these devices is based on the photocurrent induced through valence band intersubband absorption by holes and, unlike n-doped QWIPs, can utilize normal incidence illumination. Carbon and zinc were used as the p-type dopants in a low-pressure (30 Torr) vertical-geometry reactor. The Zn-doped QWIP consisted of fifty periods of 48 nm-thick undoped Al0.36Ga0.64As barriers and nominally 4 nm-thick doped GaAs quantum wells. Using normal incidence, a quantum efficiency of η = 2.5% and a detectivity of at 77K were obtained for a peak wavelength λp = 6.8 μm and a cutoff wavelength λ∫ =7.6 μm. The C-doped QWIP had 54 nm-thick Al0.31Ga0.69As barriers and exhibited a normal incidence These initial studies indicate the superiority of carbon to zinc as the p-type dopant for these structures. The detectivity of the C-doped QWIPs is about four times less than n-doped QWIPs for the same λp but have the advantage of utilizing normal incidence illumination.
Growth of GaAs and AlGaAs by MOMBE Using Phenylarsine
Authors: Abernathy C. R. , Wisk P. , Pearton S. J. , Ren F. , Bohling D. A. , Muhr G. T. 
Published: March 2011

ABSTRACTBecause of the extreme toxicity ofA3, it is highly desirable to employ gaseous As sources which contain fewer As-H bonds. Attempts to introduce compounds such as tertiarybutylarsine (TBAs) during growth by metal-organic molecular beam epitaxy (MOMBE) have been somewhat unsuccessful due to the need for pre-cracking of these materials, and to the extreme reactivity of the hydrocarbon radicals released upon their decomposition. These byproducts have been found to severely degrade various components in the growth system, and could lead to enhanced carbon uptake at low growth temperatures. Phenylarsine (PhAs) offers several advantages over the more common As substitutes as it has been demonstrated to decompose at growth temperatures of ≥575°C, and the byproducts of its decomposition are expected to be far less reactive than the byproducts of the other As precursors.In this paper we will discuss the growth of GaAs and AlGaAs at low growth temperatures (≤530°C) using PhAs as the As source. In this temperature range, the III-V growth rate is restricted due to the cracking efficiency of the PhAs. For example, at 530°C, a PhAs flow rate of ∼5.4 seem limits the growth rate to ∼95 Å/ min while a similar flow of AsH3 through a low pressure cracker allows for deposition at rates >250 Å/min. Further comparisons of the two As sources will be discussed regarding their effect on GaAs and AlGaAs growth rates from triethylgallium, trimethylgallium, and trimethylamine alane, and their effect on carbon and oxygen impurity incorporation.