bluuebunny/crossref_metadata_2025_split huggingface dataset:
In-Situ Diagnostics of Plasma-Induced Damage on GaAs by Photoreflectance Spectroscopy
Authors: Nakanishi Hideo , Wada Kazumi 
Published: March 2011

AbstractPhotoreflectance spectroscopy (PR) is used to make in-situ diagnostics of subsurface damage behavior during Ar-plasma etching of n-type GaAs. The diagnostics in-situ PR first unveil anomalous damage behavior at an early stage of plasma etch- ing: Franz-Kerdysh oscillation shows an abrupt decrease in the surface electric-field strength from 130 to 30 kV/cm within 10 sec. This indicates that acceptor-like defects with a concentration of more than 1 × 1017cm−3 are created at the very beginning of the plasma etching. The δR/R abruptly decreased to 4% in intensity upon within 5 sec. of plasma etching and subsequently recovered. This indicates that recombination centers are quickly introduced, then further plasma etching gradually removes such centers, possibly by etching the damaged layer. Photoluminescence (PL) intensity decreases to 72% but does not show any recovery, indicating that PL is dominated by recombination centers in a deeper region. Thus, in-situ PR diagnostics is the first method to provide detailed findings on new damage behavior during Ar-lasma etching.
Layered Semiconductor Photoreflectance Diagnostics
Authors: Boltar Konstantin.O. , Fedirko Valery.A. 
Published: March 2011

AbstractWe have investigated IR reflectance spectra of semiconductor structures consisting of up to 5 epitaxial GaAs/GaAlAs layers on GaAs wafer, diffused and implanted profiles in Si wafers to find the semiconductor structures parameters.
Characterization of Pseudomorphic Hemt Structures by Modulation Spectroscopy
Authors: Dimoulas A. , Zekentes K. , Androulidaki M. 
Published: March 2011

AbstractPhototransmittance has been used to investigate several pseudomorphic Al0.32Ga0.68As/In0.15Ga0.85As/GaAs high electron mobility transistor structures, with different values of the electron density ns. A lineshape analysis of the ground state transition made it possible to estimate ns, at room temperature. A signal from the Fermi-edge singularity (a manybody effect), was observed at low temperatures and the dependence of its intensity on temperature and electron density was examined.
Optical Characterization of AlInP/GaAs Heterostructures
Authors: Johnson F.G. , Kohnke G.E. , Wicks G.W. 
Published: March 2011

AbstractA 45 period GaAs/A10.54In0.46P superlattice was grown by molecular beam epitaxy using valved solid-sources to supply both the arsenic (As4) and the phosphorus (P2) group V fluxes. The room temperature optical transmission spectrum shows evidence of ground state excitons. Higher energy confined states are exhibited in photovoltage and photoreflectance spectra. Doublets corresponding to the m≈1 through m≈7 folded longitudinal-acoustic phonon modes are observed in the Raman spectrum. Analysis of these phonon doublets enables the structure of the superlattice to be determined. The interface roughness was found to be approximately 2 monolayers, and the layer thicknesses were determined to be 82 Å GaAs and 48 Å A10.54In0.46P.
In-Process Diagnostic System for Semiconductor Materials Using UHV Wafer Transfer Chamber
Authors: Uchida F. , Matsui M. , Kakibayashi H. , Kouguchi M. , Mutoh A. , Nagano H. 
Published: March 2011

AbstractWe have developed a novel stand-alone diagnostic system that can analyze a semiconductor wafer surface in each process without introducing contamination. This allows us to analyze the relationship between chemical conditions and device properties.A UHV (Ultra High Vacuum) wafer transfer chamber is used between the measuring apparatus and the semiconductor processes. The chamber vacuum system, which consists of a battery driven ion pump and a liquid N2 shroud, achieves a pressure of 2 × 10−8 Pa (corresponding to about 100 min. until one monolayer of contamination has been adsorbed).Wafer transfer lines have been constructed between semiconductor vacuum processes, CVD (Chemical Vapor Deposition) and measuring instruments, ESCA (Electron Spectroscopy for Chemical Analysis) and TEM (Transmission Electron Microscope). Our results from ESCA and TEM showed measurements that carbon contamination and oxidation was suppressed.
Simultaneous Real Time Spectroscopic Ellipsometry and Reflectance for Monitoring Semiconductor and Thin Film Preparation
Authors: An Ilsin , Nguyen Hien V. , Heyd A. R. , Collins R. W. 
Published: March 2011

AbstractThis paper describes an expansion of the capabilities of real time spectroscopic ellipsometry (SE) that results from simultaneous measurement of a reflectance spectrum RA along with the two spectra in the ellipsometric angles (Ψ,δ). RA provides information complementary to (Ψ,δ), but until now has not been exploited in real time spectroscopic applications. Earlier, we have developed a novel rotating-polarizer multichannel ellipsometer for real time studies of thin film growth that utilizes a photodiode array (PDA) detector for highspeed acquisition of (Ψ,δ) spectra. Employing this instrument with a 12.5 Hz polarizer rotation rate, three-parameter (3-p) data sets {Ψ(hv,t), δ(hv,t), RA(hv,t); 1.4≤hv≤4.5 eV} can now be obtained with a time resolution as short as 40 ms during film growth. A resilient new analysis approach based on mathematical inversion and least-squares fitting is described to interpret the 3-p data set. The 3-p approach has been successful in characterizing plasmaenhanced chemical vapor deposition (PECVD) of amorphous semiconductors, and provides the film dielectric functions and thicknesses independently at each time during film growth. RA(hV) exhibits deviations from the spectrum predicted in successful modeling of (Ψ,δ) spectra alone. These deviations result from diffuse light scattering by particulates in the plasma. We show how additional information can be extracted from the spectral dependence of the scattering loss.
Single Photon Laser Ionization as an In-Situ Diagnostic for MBE Growth
Authors: Alstrin April L. , Kunz Adina K. , Strupp Paul G. , Leone Stephen R. 
Published: March 2011

AbstractSingle photon laser ionization time-of-flight mass spectroscopy (SPI-TOFMS) is used to monitor the gaseous fluxes of Ga and Asn, during molecular beam epitaxy of GaAs. This noninvasive and real-time probe measures densities, and hence fluxes, of multiple chemical species impinging on or scattered from a substrate during conventional MBE. With single photon ionization at 118 nm (10.5 eV, ninth harmonic of Nd:YAG laser), the photon energy is large enough to ionize the species, but insufficient to both ionize and fragment. The lack of molecular dissociation of As2 and As4 greatly simplifies the interpretation of mass spectra. Additionally, the geometry of the single photon ionization TOFMS permits simultaneous film growth monitoring using RHEED. Results will be presented on the probing of scattering and desorption of III-V MBE species during GaAs growth. This technique promises to be a valuable in-situ diagnostic for III-V and II-VI MBE.
Deep–Level Transient Spectroscopy Studies of Czochralski–Grown N–Type Silicon
Authors: Tokuda Yutaka , Katoh Isao , Katayama Masayuki , Hattori Tadasi 
Published: March 2011

AbstractElectron traps in Czochralski–grown n-type (100) silicon with and without donor annihilation annealing have been studied by deep–level transient spectroscopy. A total of eight electron traps are observed in the concentration range 1010 –1011 cm −3. It is thought that these are grown–in defects during crystal growth cooling period including donor annihilation annealing. It is suggested that two electron traps labelled A2 (Ec–0.34 eV) and A3 (Ec–0.38 eV) of these traps are correlated with oxygen–related defects. It is shown that traps A2 and A3 are formed around 400 ° C and disappear around 500–600 ° C.
Study of Silicon Surface Roughness by Atomic Force Microscopy
Authors: Gilicinski Andrew G. , Rynders Rebecca M. , Beck Scotjt E. , Strausser Yale E. , Stets James R. , Felker Brian S. , Bohling David A. 
Published: March 2011

AbstractProgress is reported in developing reliable methodology for imaging silicon surfaces with the atomic force microscope (AFM). A new form of AFM, known as tapping mode AFM, has been found to provide the best quality data for surface roughness determinations. Commercially available colloidal gold spheres have been used to fabricate tip characterization standards and are used to report tip size with roughness data. Power spectral density calculations are shown to provide a useful roughness calculation based on lateral wavelength.
The Effect of Polysilicon Deposition and Doping Processes on Double-Poly Capacitors - Electrical and AFM Evaluation
Authors: Paulson W. M. , Breaux L. H. , Hegde R. I. , Tobin P. J. 
Published: March 2011

AbstractWe have characterized the surface topography of silicon films from different deposition and doping process sequences using AFM and optical reflectivity. The resulting surface structures after deposition, doping, oxide growth, and oxide removal correlate with the electrical leakage currents and breakdown voltages of double polysilicon capacitors. As-deposited amorphous films had smoother surfaces than those deposited in the crystalline state. Gas-phase diffusion doping increases the surface roughness. Only the amorphous in situ doped films retained a smooth surface following oxidation, yielding low leakage capacitors with breakdown fields above 8 MV/cm. Surprisingly, implanted amorphous films exhibited the roughest interfaces, resulting in lower breakdown fields. This study has shown that AFM provides an effective, quick, non-destructive diagnostic technique for semiconductor processing.
The Performance Study of Ion Implanter Based Medium Energy Ion Spectroscopy with Solid State Detector
Authors: Radzimski Z. J. , Yokoyama S. , Ishibashi K. , Hirose M. 
Published: March 2011

AbstractMedium-energy ion spectroscopy using a conventional ion implanter has been developed to study the properties of semiconductor subsurface regions. The system is equipped with solid state detector and operaties with He+ ion energy up to 200 keV. We have tested the system performance for various applications, such as, silicon diffusion through a thin Au layer, a low dose, low energy As implantion and damage of silicon surface caused by plasma treatment.
Semi-Insulating Behavior of Undoped Inp
Authors: Kainosho K. , Oda O. , Hirt G. , MÜller G. 
Published: March 2011

AbstractRecently, it was found that semi-insulating behavior of undoped InP can be realized by high pressure annealing of undoped high purity InP. In the present work, studies related with the achievement of the semi-insulating state are reviewed. Purification of raw materials, effect of native defects, effect of high pressure annealing, contamination of Fe are discussed. The semi-insulation mechanism is explained by the Shockley diagram. The semi-insulating state is supposed to be achieved by the annihilation of shallow donors (presumably phosphorus vacancies) and the compensation of the residual donors with a small amount of Fe deep acceptor.
Strong Visible Photoluminescence in Silicon Nitride thin Films Deposited at High Rates
Authors: Deshpande Sadanand V. , Gulari Erdogan , Brown Steven W. , Rand S.C. 
Published: March 2011

AbstractAmorphous silicon nitrogen alloy (a-Si:Nx) thin films have been deposited using a novel hot filament chemical vapor deposition (HFCVD) technique. In this method, a hot tungsten filament is used to decompose ammonia to obtain highly reactive nitrogen precursor species which further react with disilane to form silicon nitride thin films. This allows for very high deposition rates ranging from 600 Å/min to 2500 Å/min at low substrate temperatures. These films deposited at high rates show strong photoluminescence (PL) at room temperature in the visible region when excited with the 457 nm line of Ar+ ion laser. Intrinsic defects introduced into the amorphous silicon nitride matrix due to the rapid deposition rates seem to give rise to the visible PL. The PL intensity is at least 8-10 times stronger than silicon nitride films deposited by conventional plasma enhanced CVD. PL peak position of this broad luminescence was varied in the visible region by changing the film stoichiometry (Si/N ratio). The PL peak energy also scales predictably with the refractive index and optical band gap of the films. These samples showed reversible PL fatigue and also have band edge tail states characteristic of amorphous materials.
Effect of Pressure on Arsenic Diffusion in Germanium
Authors: Mitha S. , Theiss S. D. , Aziz M. J. , Schiferl D. , Poker D. B. 
Published: March 2011

AbstractWe report preliminary results of a study of the activation volume for diffusion of arsenic in germanium. High-temperature high-pressure anneals were performed in a liquid argon pressure medium in a diamond anvil cell capable of reaching 5 GPa and 7500 C, which is externally heated for uniform and repeatable temperature profiles. The broadening of an ion-implanted arsenic profile was measured by Secondary Ion Mass Spectrometry. Hydrostatic pressure retards the diffusivity at 575°C, characterized by an activation volume that is +15% of the atomic volume of Ge. Implications for diffusion mechanisms are discussed.
Recent Developments in Doping Techniques for Compound Semiconductors
Authors: Cunningham J. E. , Tsang W. T. 
Published: March 2011

AbstractWe report new methods to dope compound semiconductors. First, we demonstrate the concept of doping engineering whereby it becomes possible to tailor the activation energy of the dopant in a host semiconductor for the first time. In this application, the band offset of a thin, sacrificial semiconductor is used to lower the activation energy of the dopant below its value in the host semiconductor. This allows the freedom to control dopant activity in ways not accessible to a uniformly placed dopant. We chose δ-Be-AlGaAs/GaAs as a model example and show the hole binding energy is reduced by a factor of five. Secondly, we demonstrate overcoming the p-type solubility limit in GaAs by use of monolayer δ-Be in a GaAs base of an HBT. Here, an effective hole concentration of > 1021cm−3 is measured in real devices. We present a qualatative view of doping solubility limitations that are controlled by surface processes.
Annealing Effect on Photoluminescence Properties of Be-Doped MBE GaAs
Authors: Shibata Hajime , Makita Yunosuke , Yamada Akimasa 
Published: March 2011

AbstractLow temperature (2° K) photoluminescence (PL) measurements were performed for the wavelength (λ) region from 800 to 1600 nm on Be–doped GaAs grown by molecular beam epitaxy (MBE) for wide range of net hole concentration at room temperature (p) up to 2 x 1020 cm−3 after annealing at 850 °C for 20 minutes. The annealing procedure formed several new PL emission bands associated with deep levels appeared between 0.4 and 1.4 eV. The most intensive new PL band appeared at around 1.2 eV with a band width of about 0.2 eV for all samples investigated. Its peak position and band width were observed to shift slightly toward lower energy side and increase, respectively with increasing p. An additional two sharp bands appeared overlapping the main band at around 1.31 and 1.35 eV for p less than 1 x 1018 cm−3. New broad band formation was also observed at around 1.0 eV in the same samples. In addition, a new prominent PL band was found at about 1.35 eV in the as-grown samples with p = 5 ∼ 6 x 1017 cm−3, which disappeared entirely after annealing. The formation and annihilation mechanism of these deep levels after annealing can be presumably attributed to Be redistribution from Ga sites to As sites and interstitial sites to Ga or As sites, driven by the formation of As vacancies (V As) due to As evaporation from samples during annealing.
Oxygen Doping of GaAs During Omvpe Controlled Introduction of Impurity Complexes
Authors: Park Y. , Skowronski M. , Rosseel T.S. , Manasreh M.O. 
Published: March 2011

AbstractGaAs epilayers have been grown by Organo-Metallic Vapor Phase Epitaxy using dimethylaluminum methoxide as a dopant source. This compound contains a strong aluminumoxygen bond which is thought to remain intact during low temperature deposition and result in the incorporation of Al-O as a complex. Incorporation of aluminum and oxygen was investigated by Secondary Ion Mass Spectroscopy as a function of growth conditions: growth temperature, growth rate, V/III ratio, reactor pressure and dopant mole fraction. High doping levels up to 1020 cm−3 (for both oxygen and aluminum) were achieved without degradation of surface morphology andlor precipitation of a second phase. Oxygen concentration is lower than that of aluminum for all investigated growth conditions but at low deposition temperatures oxygen/aluminum ratios approach 1, indicating that Al-O is incorporated as a pair. Infrared absorption measurements in the 600-1200 cm−1 range did not detect well known isolated oxygen localized vibrational modes (LVM). Also in layers grown at low temperatures the intensity of isolated aluminum LVM at 362 cm−1 is much smaller than the concentration obtained by SIMS. Both observations prove that oxygen not only is incorporated as an Al-O pair but remains bonded in the bulk of the layer. Low temperature photoluminescence measurements indicate that the A1-O complex is electrically active in GaAs, forms a deep level within the GaAs band gap, and serves as an efficient non-radiative recombination center. Near band edge luminescence intensity correlates well incorporation of oxygen. The Al-O pairs act as deep acceptors in GaAs and cause the compensation of shallow tellurium donors.
Identification of Diffusion Associated Defects at III-V Semiconductor Heterostructures
Authors: Viturro R. Enrique , Wicks Gary W. 
Published: March 2011

AbstractCathodoluminescence spectroscopy is used to identify diffusion-associated III-V semiconductor defects and establish their role in AlGaAs/GaAs intrinsic and n-type impurity induced interdiffusion (Si, Ge, S, and Se) for various ambient conditions, As- and Ga-rich. These identifications involves the study of the temperature and composition dependence of these deep levels and their correlation with theoretical calculations. Our results reveal Column III vacancies and their complexes as the sole mediators of diffusion.
Proton Irradiation Damage in Zn and Cd Doped InP
Authors: Rybicki George C. , Williams Wendell S. 
Published: March 2011

AbstractDeep Level Transient Spectroscopy (DLTS) was used to study the defects introduced in Zn and Cd doped Schottky barrier diodes by 2 MeV proton irradiation. The defects H3, H4 and H5 were observed in lightly Zn doped InP, while only the defects H3 and H5 were observed in more heavily Zn doped and Cd doped InP. The defect activation energies and capture cross sections did not vary between the Zn and Cd doped InP.The concentration of the radiation induced defects was also measured. The introduction rate of the defect H4 in the lightly Zn doped InP and the introduction rate of the defect H3 in the heavily Zn and Cd doped InP were about equal, but the introduction rate of the defect H5 varied strongly among the three types of material. The introduction rate of H5 was highest in the heavily Zn doped InP but the lowest in the heavily Cd doped InP, even though they were doped comparably. As a result, the total defect introduction rate was lowest in the highly Cd doped InP.The results can be interpreted in terms of the models for the formation and annealing of defects, and by the different diffusion rates of Zn and Cd in InP.
Vacancy Injection Enhanced Al-Ga Inter-diffusion in Si FIB Implanted Superlattice
Authors: Chen P. , Steckl A.J. 
Published: March 2011

AbstractThe Al-Ga inter-diffusion induced by Si FIB implantation and subsequent RTA were investigated in an Al0.3Ga0.7As/GaAs superlattice with equal 3.5 nm barrier and well widths. Si++ was accelerated to 50 kV as well as 100kV and implanted parallel to sample normal at doses ranging from 1013 to 1015/cm2. The effect of rapid thermal anneal of 10s at 950°C was characterized by SIMS technique. In the implanted region, the inter-diffusion as well as compositional mixing were significantly enhanced. An ion dose as low as 1×1014/cm2 results in a two-order of magnitude increase in the inter-diffusion coefficient, to a value of 4.5×10-14 cm2/sec, in contrast to 1.3×10-16 cm2/sec from RTA-only. This produces a mixing parameter of σ90%. A strong depth dependence of the mixing process was observed at implantation energy of 100keV with a pinch-off region being formed at certain depth. It is noticed that the depth where this enhancement occurred is not associated with either the maximum concentration of Si ions or of vacancies. Instead, it represents the positive maximum of the second derivative of the vacancy profile, which in turn represents the vacancy injection generated by presence of a transient vacancy concentration gradient. Based on this, a theoretical model was developed using vacancy injection as responsible for mixing.
Improvement of the Structural Quality of GaAs Layers Grown on Si with LT-GaAs Intermediate Layer
Authors: Weber Zuzanna Liliental , Fujioka H. , Sohn H. , Weber E.R. 
Published: March 2011

AbstractSuperior electrical and optical quality of GaAs grown on Si with an inserted low-temperature (LT)-GaAs buffer-layer was demonstrated. Photoluminescence intensity was increasing and leakage current of Schottky diodes build on such a structure was decreasing by few orders of magnitude. These observations were correlated with structural studies employing classical and high-resolution transmission electron microscopy (TEM). Bending of the threading dislocations and their interaction was observed at the interface between a cap GaAs layer and the LT-GaAs layer. This dislocation interaction results in the reduction of dislocation density by at least one order of magnitude or more compared for the GaAs layers with the same thickness grown on Si. The surface morphology of the cap GaAs layer is improving as well.
Compositional Modulations and Vertical Two-Dimensional Arsenic-Precipitate Arrays and in Low Temperature Grown Al0.3GA0.7AS
Authors: Hsieh K.Y. , Hwang Y.L. , Zhang T. , Kolbas R.M. 
Published: March 2011

AbstractCompositional modulations and arsenic precipitates in annealed A10.3Ga0.7As layers which were grown at a low substrate temperature (200° C) by molecular beam epitaxy (MBE) were studied by transmission electron microscopy (TEM). These layers were used as surface layer which were applied on metal-insulator-semiconductor (MIS) diode. The planar and cross sectional TEM micrographs reveal that compositional modulations occurred when the thickness of LT AIGaAs was over 1500Å. The wavelength of the modulations varies between 100-200 Å and the direction of the modulation is along \011]. The arsenic precipitates were formed after annealed and the distribution of them followed the compositional modulation. Vertical two dimensional arsenic-precipitates arrays were arranged in the low aluminum constitute region. These novel microstructures result from the strain-induced spinodal decomposition and the arsenic precipitates redistribution process.