bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Technique to Generate Conductive Paths in Dielectric Materials
Authors: Desilva M. J. , Pedraza A. J. , Lowndes D. H. , Godbole M. J. 
Published: March 2011

AbstractWe have developed a new two-step process to generate a metallic pattern on dielectric materials. This method employs ultraviolet (uv) laser irradiation followed by electroless deposition. A few laser pulses are required to generate the pattern. After immersion in an electroless bath, the metal film is deposited only on the uv exposed area. Results of the application of this method to aluminum nitride and alumina are presented. The laser irradiation step is very fast, and the electroless deposition is simplified because it does not require any special seeding to promote activation, i.e. laser irradiation activates the dielectric surface for electroless deposition. In addition, the laser-induced activation of the insulator is maintained for a very long time allowing electroless deposition to be performed many months after irradiation. Patterns in the tens of microns can be produced on laser-exposed substrates. Pull tests have been performed to determine the bond strength. We have found that the bond strength can be further increased by annealing.
Real-Time in Situ Monitoring of Defect Evolution at Widegap II-VI/GaAs Heterointerfaces during Epitaxial Growth
Authors: Rouleau C.M. , Park R.M. 
Published: March 2011

AbstractWe report the real-time in situ observation of heterointerface dislocation formation during the growth of lattice-mismatched widegap II-VI/GaAs heterostructures. Such observations were made by employing a near-normal incidence HeNe laser probe during epitaxial growth which generated both a laser reflection interferometry (LRI) signal as well as an elastically scattered laser light (ELLS) signal. We believe that the scattered light signal is generated at the II-VI/GaAs heterointerface based on the observation of a π phase difference between the LRI and the ELLS signals which were monitored simultaneously. We suggest, therefore, that the observed ELLS signal is a consequence of dislocation formation at the heterointerface which occurs due to plastic deformation in lattice-mismatched systems.
Contactless Electromodulation Characterization of Compound Semiconductor Surfaces and Device Structures
Authors: Woodall J.M. 
Published: March 2011

AbstractThis paper will review the use of contactless electromodulation methods, such as photoreflectance (PR) and contactless electroreflectance (CER), to characterize the electronic properties of compound semiconductor surfaces exposed to different growth and post-growth conditions. Also the characterization of properties critical to device performance can be evaluated. For example, using PR and CER it has been found that there is a lower density of surface hole traps than electron traps in certain as-grown MBE (001) GaAs samples and that this condition persists even after air exposure. This behaviour is in contrast to other samples, including both bulk and MBE grown (001) surfaces in which the Fermi level is pinned mid-gap for both n- and p-type structures. We also have observed that Ar+ bombardment under UHV conditions results in Fermi level pinning close to the conduction band edge and that thermal annealing restores mid-gap pinning. Finally, using PR we are able to characterize the electric fields and associated doping levels in the emitter and collector regions of heterojunction bipolar transistor structures (fabricated from III-V materials), thus demonstrating the ability to perform inprocess evaluation of important device parameters.
Optical Characterization of InGaAs/InP Quantum Wires and Dots
Authors: Gu S.Q. , Reuter E. , Xu Q. , Chang H. , Panepucci R. , Adesida I. , Bishop S.G. 
Published: March 2011

AbstractHigh resolution electron beam lithography and reactive ion etching in methane-hydrogen (CH4/H2) plasmas have been used to fabricate InGaAs/InP open quantum well wires (QWW) with widths ranging from 200 to 40 nm and quantum dots (QD) with diameters ranging from 600 to 100 nm. Low temperature photoluminescence (PL) spectra were investigated in these nanostructures as a function of excitation intensity, wire width, and dot diameter. The peak emission of the dry-etched 40 nm wires is shifted to higher energies by about 2 meV as compared to 100 nm wires. This “open wire” result is consistent with results reported for buried InGaAs/InP wires of the same width. The blue-shift of the PL peak reaches 10 meV in QDs as their diameters decrease to 100 nm. The magnitude of the observed blue shift in the QDs is larger than the blue-shift predicted on the basis of quantum confinement for the same size dots.
Photoreflectance Study of Modulation-Doped GaAs/GaAlAs Quantum Dots Fabricated by Reactive-Ion Etching
Authors: Wang P.D. , Torres C.M. Sotomayor , Holland M.C. , Qiang H. , Pollak F.H. , Gumbs G. 
Published: March 2011

AbstractUsing contactless photoreflectance at 300K and 77K we have investigated the intersubband transitions from two modulation-doped GaAs/GaAlAs quantum dot (QD) arrays fabricated by reactive-ion etching (RIE). The samples consisted of 8 nm decoupled GaAs/GaAlAs quantum wells with dot sizes (lateral dimensions) of 60 and 100 nm. The lineshapes of the “IC-IH” and “IC-IL” features were indicative of a screened exciton, i.e., the derivative of a broadened twodimensional density of states (step function), due to the presence of the electron gas. On the other hand, even at 300K the “2C-2H“ features exhibited a well-defined sharp excitonic lineshape, i.e., derivative of a Gaussian profile. Even at room temperature it is possible to detect the effects of the lateral quantum confinement. We have observed a 2 meV blue shift of the “2C-2H” feature of the 60 nm QD array in relation to the 100 nm QD array. At 77K we have found evidence for a “parabolic-like” in-plane confining potential on the smaller QD array. This experiment demonstrates the considerable utility of PR in studying these reduced dimensional systems.
Influence of Growth Conditions on the Modulation Mechanism of Photoreflectance Spectra of Single InGaAs/InAlAs Quantum Wells
Authors: Baltagi Y. , Bru C. , Benyatrou T. , Garcia-Perez M.A. , Guillot G. , Gendry M. , Leclercq J.L , Drouot V. , Hollinger G. 
Published: March 2011

AbstractUsing Photoreflectance (PR) measurements, we have investigated In0.53Ga0.47As single quantum wells (SQW) with In0.52Al0.48As barriers grown by MBE on InP substrates. Unusual lineshapes of PR spectra are observed for the fundamental transition in some of the SQW. This phenomenon is shown to be independent on the widths of both the SQW (5nm or 10nm) and the surface barrier layer (between 65nm and 300nm). PR spectra are recorded at different temperatures and in different samples, as well as with a secondary pump laser beam. From these measurements, it is concluded that interface defects exist in the SQW grown at 525°C without growth interruption. Such defects are clearly evidenced in room temperature PR experiments and confirmed by PL measurements.
Raman Scattering Characterization of Ultrathin Films of β-SiC
Authors: Choo Ahn Goo , Tlali Spirit , Jackson Howard E. , Li J. P. , Stecki Andrew J. 
Published: March 2011

AbstractRaman scattering has been used to characterize ultrathin films of β-SiC, ranging in thickness from 38 nm to 240 nm. These films were prepared on the surface of a <100> Si substrate by a carbonization process at a temperature of 1300°C. In each case, the LO phonon near 970 cm−1 and the TO phonon near 795 cm−1 are observed, indicating the formation of β-SiC crystal. The Raman linewidths and peak positions indicate evidence of nonuniform stress and disorder. The Raman intensity of the TO phonon is nearly twice the intensity of the LO phonon measured both with and without the Si substrate, which indicates that the crystal growth was not entirely confined in the <100> direction.
Hydrocarbon Ecr Reactive Ion Etching of III-V Semiconductors with Sims Plasma Probe Diagnostics
Authors: Melville Douglas L. , Simmons J.G. , Thompson D.A. 
Published: March 2011

AbstractThe advantages of in-situ SIMS plasma probe diagnostics are highlighted in low pressure hydrocarbon ECR reactive ion etching (RIE) of III-V materials. Three aspects of the RIE process are investigated. First, the dominant ion species in a CH4/H2/Ar plasma are recorded at various chamber pressures, ECR powers, CH4/(CH4+H2) gas flow ratios and microwave cavity tuning. These studies have improved our understanding of the effects of these parameters on the relative concentrations of reactive precursor species in the plasma and have led to more rapid optimization of the etch system. Secondly, SIMS has been used for identification of reaction products from the III-V surface at the optimized plasma conditions. The Ar diluted mixture gives rise to significant levels of group V hydrides and organometallic compounds and the dominant group III volatile ions have been positively identified as dimethyl species. The third and final aspect reported is the application of volatile product identification to endpoint detection. In lcm2 multiple quantum well samples, layers as thin as 50Å are easily distinguishable.
In-Situ Monitoring by Mass Spectrometry for GaAs Etched with An Electron Cyclotron Resonance Source
Authors: Kahaian D. J. , Pang S. W. 
Published: March 2011

AbstractQuadrupole mass spectrometry (QMS) has been used as an in-situ diagnostic technique for GaAs etched with an electron cyclotron resonance source. Changes in the detected signal intensities for reactive species and etch products have been related to corresponding changes in the etch rate as several process parameters were varied. The detected 75As+ and to a lesser degree, 35C1+ and 70C12+, were observed to follow etch rate as microwave power, rf power, source to sample distance, temperature, and pressure were varied. The self-induced dc bias (IVdcl) determines the etch rate dependence on etch time. The time delay before saturation of the monitored 75As+ signal corresponding to a constant etch rate is inversely proportional to IVdcl. The addition of N2/O2 in a 4:1 ratio to constitute 15% of the total discharge resulted in a 95% decrease in the intensity of the monitored 75As+ signal. The measured etch rate decreased by 75%.
AIGaAs Microelectronic Device Processing Using an as Capping Layer
Authors: Grepstad J.K. , Husby H. , Bernstein R.W. , Fimland B.-O. 
Published: March 2011

AbstractThe case for incorporating an arsenic capping layer in compound semiconductor device processing has been investigated with x-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED) and scanning electron microscopy (SEM). The As cap was found to be stable upon exposure to common processing chemicals, such as acetone, photoresist, developer, and N-methyl-2-pyrrolidone, a common polyimide solvent. A clean, c(4×4)-reconstructed GaAs(001) surface was recovered after thermal desorption of the cap in ultra-high vacuum, for a sample exposed to standard (maskless) photolithography. We also report a new technique for reactive decapping at room temperature, using a beam of hydrogen radicals (H*). Pattern definition in the As cap with ∼ 5 μm linewidth was demonstrated, using this technique. However, XPS and SEM data for the H*-etched specimens showed clear evidence of superficial gallium (sub)oxide and of As residues along the photoresist mask edges. This novel method of As cap patterning thus needs further refinement, before being useful to III-V device processing.
Optical Emission End-Point Detection for Via Hole Etching in InP and GaAs Power Device Structures
Authors: Pearton S. J. , Ren F. , Abernathy C. R. , Constantine C. 
Published: March 2011

AbstractNarrow (∼30 μm ϕ) via holes have been etched in both InP and GaAs substrates using either C12/CH4/H2 /Ar or BC13/C12 discharges, respectively. High density (∼5×1011 cm−3), low pressure (1 mTorr for C12/CH4/H2/Ar or 15 mTorr for BC13/C12) conditions, combined with sidewall passivation obtained using AZ 4620 photoresist masks, produce the correct profiles for subsequent metallization to complete the via connection. Optical emission monitoring of the 417.2 nm Ga line during GaAs etching or of the 325.6 nm In line during InP etching provided a sensitive, non invasive and reliable indicator of endpoint for both types of substrates. The intensity of these lines was proportional to the microwave input power at fixed dc bias and pressure. The via holes are suitable for a range of InP and GaAs microwave power devices, including Heterojunction Bipolar Transistors and High Electron Mobility Transistors.
Real-time Monitoring and Control of Silicon Epitaxy Using Emission Fourier Transform Infrared Spectroscopy
Authors: Zhou Z.H. , Kim H. , Reif Rafael 
Published: March 2011

AbstractReal-time epi-film thickness is measured by an Emission Fourier Transform Infrared Spectrometer (E/FT-IR). The E/FT-IR takes advantage of the heated wafer as the source of IR radiation. In our experiments, wafers were cleaned using in-situ ECR hydrogen plasma followed by film growth. The cleaning and deposition processes were monitored in real-time using the E/FT-IR technique. We have demonstrated the application of E/FT-IR for observing real-time growth rates and incubation times. Based on these real-time observations, the predeposition plasma cleaning process and the deposition process can be effectively monitored and controlled in real-time. Application of E/FT-IR in optimizing the predeposition hydrogen plasma cleaning process was demonstrated.
Relationship Between Minority Carrier Parameters and Solar Cell Characteristics of Electromagnetic Cast Polycrystalline Silicon
Authors: Suzuki Eiichi , Kaneko Kyojiro , Nunoi Toru 
Published: March 2011

AbstractThe relationship between minority carrier properties and solar cell characteristics of electromagnetic (EM) cast polycrystalline Si has experimentally been investigated. The minority carrier lifetime τ and diffusion coefficient D were evaluated by a novel dual mercury probe method. The solar cell characteristics, e.g., a conversion efficiency η were measured by fabricating experimental solar cells using the corresponding wafers. The wafer showing high-η (13.1%) has relatively high τ (av. 8.2 μs) with small variation of I) (av. 29.6 cm2/s). On the contrary, the low-η (11%) wafer shows low τ (av. 1.1 μs), including some inferior portions with very low τ of less than 0.5 μs. It is also shown that D drastically deteriorates with decreasing τ if τ is less than around 2 μs. To realize high efficiency polycrystalline solar cells, the wafers with high value of τ and without considerably low-τ portions are needed.
Surface Photovoltage Measurement of Minority Carrier Diffusion Lengths Exceeding Wafer Thickness: Application to Iron Monitoring with Part Per Quadrillion Sensitivity
Authors: Kontkiewicz A.M. , Lagowski J. , Dexter M. , Edelman P. 
Published: March 2011

AbstractWe discuss an approach to iron concentration determination in silicon, based on wafer-scale surface photovoltage measurement of the minority carrier diffusion length in the millimeter range. The approach combines two novel aspects: it overcomes the diffusion length to wafer thickness ratio limitation of previous SPV methods, and it employs iron separation from other recombination centers using rapid photo-dissociation of iron-boron pairs. The wafer thickness limitation was eliminated by using the correct theoretical SPV wavelength dependence instead of simplified asymptotic diffusion length form adopted in all previous treatments and valid only for diffusion lengths much shorter than the wafer thickness. Photo-dissociation of Fe-B pairs and measurement of the corresponding decrease of the L value (caused by creation of iron intersticials) enables iron detection in typical silicon wafers in times of seconds with a sensitivity in the low 108 atoms/cm3 range.
Use of Synchrotron White Beam X-Ray Topography to Characterize IR Detector Manufacturing Processes
Authors: Dudley M. , Wu Jun , Larson D. J. , Dimarzio D. 
Published: March 2011

AbstractIt has been have demonstrated that synchrotron white beam x-ray topography can be used to characterize IR detector materials at nearly every stage in the manufacturing cycle, including: as-grown CdZnTe single crystal boules; substrate wafers cut from different positions in the boules; thin films grown on characterized wafers; and HgCdTe focal plane arraystructures. Special diffraction geometries have been developed, taking advantage of the broad wavelength spectrum, large beam size, and high intensity of the synchrotron radiation source, to enable rapid and non-destructive assessment of defect densities and strain distributions after each processing step. This diagnostic method has important implications for increasing the producibility of focal plane arrays. Boule characterization can reveal defects, grain orientation, interfaces and strains, and provides guidance for optimal slicing. Wafer characterization produces multiple topographic images, providing both defect mapping and depth profiling in a single exposure. Finally, x-ray topography of HgCdTe focal plane array test articles reveals subsurface damage not observable by optical or IR microscopy. The applicability of this technique to evaluate yield, quality, and reproducibility will be discussed.
Effects of Halogen-Containing Gas Plasma and Rapid Thermal Anneal Treatment on the Reactive Ion Etched Silicon
Authors: Kwon Kwang-Ho , Kim Bo-Woo , Park Hyung-Ho , Kang Jin-Yeong , Yeom Gun-Yung 
Published: March 2011

AbstractThe effects of SF6 and NF3 gas plasma treatments, and succesive rapid thermal anneal (RTA) treatment for the recovery of modified silicon surface due to CHF3/C2F6 plasma have been investigated using X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). XPS analyses have revealed that NF3 and SF6 plasma treatments are effective for the removal of residue layer. SIMS results show that penetrated impurities in the contaminated silicon substrate reduce through the additional RTA treatment. The effects of NF3, SF6 plasmas, and additional RTA treatments for the recovery of reactive ion etched silicon surface has been also studied by measuring the electrical performance of the silicon devices.
A New Environmentally Stable Posyitve Tone Chemically Amplified Resist System - KRS
Authors: Iiuang Wu-Song , Kwong Ranee , Katnani Ahmad , Khojasteh Maitoud , Lee Kim Y. 
Published: March 2011

AbstractIt is known that one of the main shortcomings of chemically amplified resist systems is their sensitivity to airborne base contaminants. The contaminants cause unpredictable linewidth variations deeming the resist incompatible with manufacturing. Besides other issues, this drawback has greatly contributed to the slow introduction of DUV into manufacturing and discouragcd most semiconductor manufactures from including DUV in their strategic plans. In this paper, we present a new positive tone chemically amplified photoresist system which is resilient to airborne base contaminants and it shows stable linewidth for more than 24 hours delay between exposure and development. This resist has high sensitivity (17-18 mj/cm2), high contrast (7), high resolution (0.35 um with λ = 248 rm and NA = 0.37) and large process latitude in deep-UV lithography. This resist also exhibits high resolution (0.1 um in 0.35 um thick resist) in E-beam lithography at a sensitivity of about 10 uC/cm2. Both lithographic systems (deep-UV and E-beam) yield nearly vertical profiles in the resist images.
Infrared and Ultraviolet Analysis of Dual-Ion Implanted Gaas
Authors: Lacquet Beatrys M. , Aizenberg Gustavo E. , Swart Pieter L. 
Published: March 2011

AbstractSemi-insulating <100> GaAs was implanted with 170 ke V H+ and P+ ions at room temperature using a PH3 source. Fourier analysis of the bilinear transformed optical reflectance data in the infrared region of the spectrum indicated the presence of two damaged layers at different depths from the surface: (i) a deep inhomogeneous layer of low damage produced by the protons and (ii) a thin amorphized surface layer which was produced by phosphorus ions. The position and refractive index at the peak of the assumed gaussian damage profile caused by the protons, as well as the standard deviation of the profile, were estimated rapidly from the processed data. The thickness and refractive index of the surface layer were also estimated from this analysis. The presence of the amorphized surface layer was evident from the reflectance in the ultraviolet where shift and broadening of the reflectance peaks associated with the Van Hove singularities, were observed.
Reliable Impurity Identification in Inp
Authors: Schnoes M. L. , Harris T. D. , Pearton S. J. , Di Giuseppe M. A. , Bhat R. , Cox H. M. 
Published: March 2011

AbstractLow temperature, resonantly excited photoluminescence (PL) has proven to be the method of choice for impurity identification in GaAs. InP has suffered from insufficient impurity binding energy data to benefit similarly. We will report results of selectively-excited donor-acceptor pair spectroscopy for acceptor identification in InP. Ion implantation doping of high purity InP is used for generation of known impurity samples. Progress toward a complete database of acceptor binding energies in InP is reported. We will discuss the results of high magnetic field low temperature resonant photoluminescence spectroscopy for donor identification in InP. The success of donor ion implantation studies will be included. This data should provide direction for efforts in growing high purity InP by MOCVD and gas source MBE.
Correlation Between Electrical Properties and Residual Defects in Se+-Implanted InP After Rapid Thermal Annealing
Authors: MÜller P. , Bachmann T. , Wendler E. , Wesch W. , Richter U. 
Published: March 2011

Abstract>100> -semiinsulating InP was implanted with 600 keV Se-ions at temperatures between 300K and 425K with an ion dose of 1 ×1014 cm−2. After capping the samples with about 120 nm siliconoxynitride annealing was performed at 700°C up to 975°C using a graphite strip heater system. The annealed samples were analyzed with Rutherford backscattering, electron microscopy and conventional Hall measurements. The results show, that a strong correlation exists between defects remaining after annealing (for instance dislocations, loops, microtwins) and the measured electrical properties. An implantation temperature ≦ 395K and annealing at least at 800°C for 50 s is necessary to obtain high performance electrically active layers. The activation of selenium in InP can be well described using a simple thermodynamical model. The model yields an activation energy of EA = (1.0 ± 0. 1) eV which can be understood as the energy necessary to split-up selenium-vacancy-complexes and a diffusion energy of Ed = (2.0 ± 0.2) eV representing material transport of the semiconductor material.
Deep Level Characterization and Passivation in Heteroepitaxial Inp
Authors: Chatterjee B. , Ringel S. A. , Sieg R. , Weinberg I. , Hoffman R. 
Published: March 2011

AbstractDeep levels in MOCVD grown p-InP on GaAs substrates have been investigated by Deep Level Transient Spectroscopy (DLTS). The effect of hydrogenation on the electrical activity of these levels has been studied through a combination of DLTS and Photoluminescence (PL) measurements. DLTS measurements indicate a drop of trap density from σ 5 × 1014 cm−3 to σ 1 × 1012 cm−3 after hydrogenation. Annealing at 400°C reactivated only the dopants, while temperatures above 600°C were necessary for deep-level reactivation. This combined with a logarithmic dependence on fill pulse time, indicate that at least one broad DLTS peak is associated with dislocations. The PL the DLTS results show that the dislocation related traps are passivated by hydrogen, preferentially over the dopants and that a wide annealing window exists for dopant reactivation.