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CreatorTitleDescriptionSubjectDate
1 Stringfellow, Gerald B.Radiative pair transitions in p-type ZnSe:Cu crystalsShallow levels with an ionization energy of 0.012 eV play an important role in the photoelectronic properties of p-type ZnSe:Cu crystals. These levels exhibit the characteristics of the higher-lying member of an imperfection pair involved in luminescence emission, as well as of a trap determining lo...Ionization energy; Luminescence emission; Crystals1968
2 Stringfellow, Gerald B.Dislocations in GaAs17-xPxDislocations, their origins, and their effects on photoluminescence efficiency have been studied in GaAs1-xPx single crystals grown by vapor phase epitaxy. Dislocations were observed using etch pit, optical-transmission microscopy, and x-ray topography techniques. Two types of dislocations are grown...Photoluminescence efficiency; Growth mechanism; Optical transmission microscopy1969
3 Stringfellow, Gerald B.Electrical properties of nitrogen doped GaPThe electrical properties namely, electron concentration and mobility, have been investigated in the temperature range from 53 to 400 K for undoped and nitrogen-doped VPE GaP.Electron concentration; Ionization energy; Electron mobility1975
4 Stringfellow, Gerald B.Mechanism for liquid phase epitaxial growth of nonequilibrium compositions producing a coherent interfaceA model is presented for growth by so-called composition pulling, wherein an epitaxial deposit grows coherently but with a composition different from that which would be in bulk equilibrium with the liquid phase from which growth occurs. The breakdown of coherent growth occurs when a dislocation nuc...Lattice-matching overgrowths; Composition pulling; Dislocation interface1977
5 Stringfellow, Gerald B.Electron mobility in AlxGa1-xAshe electron mobility in AlxGa1-xAs grown by several techniques has been studied to determine whether VPE layers are more highly compensated than comparable LPE layers. The techniques used to grow layers included (1) organometallic VPE using Al(CH3)3, AsH3, and Ga(C2H5)3 or Ga(CH3)3, (2) ''hybrid'' o...Alloys; Organometallics1979-06
6 Stringfellow, Gerald B.Deep electron traps in organometallic vapor phase grown AlGaAsDeep electron traps have been studied by means of deep level transient spectrosocopy in type nominally undoped and interntionally te doped Al Ga As epitaxial layers which were grown by vapor phase epitaxy from organometallic compounds (OMVPE). Three main deep electron levels are present in undoped m...Vapor phase epitaxy; Shallow impurity identity; Optoelectronic device performance1980
7 Stringfellow, Gerald B.Photoluminescence of Shallow Acceptors in Epitaxial AlGaAsThe low-temperature (2 K) photoluminescence (PL) of AlxGa1-xAs (0<x<0.25 was studied in an effort to characterize shallow acceptors in material grown by organometallic vapor phase epitaxy and liquid phase epitaxy techniques. The dominant shallow acceptor in nominally undoped AlxGa1-xAs specimens gro...Photoluminescence; Acceptors; Doping1980
8 Stringfellow, Gerald B.Electron mobility in compensated GaAs and AlGaAsThe dependence of electron mobility on temperature in GaAs and Al Ga As indicates that for cimpensated material a term having causes a significant reduction in the mobility measured at high temperatures. The magnitude of the term in mobility, denoted is found to be linearly proportional to the compe...Unspecified mobility; Reduced mobility; Space charge regions1980
9 Stringfellow, Gerald B.Vapor phase interaction of trimethylaluminum with graphite during OMVPEWe have used a molecular beam mass spectrometer to study the interaction of trimethylaluminum (TMA) with graphite surfaces. Our results indicate that a strong adsorption effect occurs which explains phenomena occuring during OMVPE growth of AlxGa1-xAs, such as long A1 transients, oxygen gettering, a...Organometallic vapor phase epitaxy; Thermodynamics; Graphite; Trimethylaluminum1982
10 Stringfellow, Gerald B.Thermodynamic aspects of organometallic VPEOrganometallic vapor phase epitaxy (OMVPE) is a new crystal growth technique which is rapidly gaining popularity due to its simplicity, flexibility and proven ability to grow excellent quality III/V compounds and alloys for device applications.Organometallic vapor phase epitaxy; Thermodynamics1982
11 Mathews, V. JohnOn using the short-time unbiased spectrum estimation algorithm for estimating time delays and magnitude squared coherence functionsThis paper introduces novel applications of the short-time unbiased sprectral estimation (STUSE) algorithm, which adds biased estimates to yield unbiased spectral estimates. It is shown that STUSE algorithm is an effective tool for estimating time delays and magnitude-squared coherence (MSC) functio...1983
12 Mathews, V. JohnDetection and estimation with fixed lag for abruptly changing systemsThe problem of state estimation and system structure detection for discrete-time stochastic systems with parameters which may switch among a finite set of values is considered. The switchings are modeled by a semi-Markov, or Markov, chain with known transition statistics. A fixed time delay (lag) is...1983
13 Stringfellow, Gerald B.Miscibility gaps and spinodal decomposition in III/V quaternary alloys of the type AxByC1−x−yDThermodynamic concepts have been developed for the calculation of solid-phase miscibility gaps and spinodal decomposition in quaternary alloys of the type AxByC1−x−yD. These concepts have been applied to the analysis of III/V quaternary alloys using the delta-lattice-parameter (DLP) solution mod...Thermodynamics; Quartenary alloys; Coherent decomposition1983-01
14 Mathews, V. JohnAdaptive realizations of the maximum likelihood processor for time delay estimationAbstract-This correspondence introduces an adaptive realization of the maximum likelihood (ML) processor for time delay estimation (TDE). Also presented is a modified ML processor, which requires less computations but still performs better than the other when implemented in an adaptive way. Widrow'...1984
15 Mathews, V. JohnAdaptive nonlinear digital filter with sequential regression algorithmThe purpose of this paper is to introduce an adaptive nonlinear digital filtering algorithm which use the sequential regression (SER) method to update the second order Volterra filter coefficients in a recursive way. Conventionally, the SER method has been used to invert large matrices which result ...1984
16 Mathews, V. JohnAdaptive realizations of the phase transform for time delay estimationABSTRACT This paper introduces two recursive realizations of the Phase Transforn (PHAT) processor for tine delay estimation (TOE), using a simple one-pole lowpass filter and the least mean square (LMS) adaptive filter, respectively. It is shown that these adaptive methods are very effective in redu...1984
17 Mathews, V. JohnSpectral leakage suppression properties of linear and quadratic windowingAbstract-It is shown that the leakage suppression properties of segment averaging spectrum estimation methods using hear windows and equivalent quadratic windows are asymptotically the same, under the assumption that segments relatively far apart are uncorrelated. Thus, for large data lengths, one ...1984
18 Stringfellow, Gerald B.; Cohen, Richard M.Organometallic vapor phase epitaxial growth of high purity GaInAs using trimethylindiumGax In1−xAs lattice matched to the InP substrate (x=0.47) has been grown by organometallic vapor phase epitaxy using trimethylindium (TMIn) and trimethylgallium (TMGa) as the group III sources and AsH3 as the As source. In a simple, horizontal, atmospheric pressure reactor, the GaInAs growth proce...Electron mobilities; Photouminescience; Fabricate modulation1984-03-01
19 Stringfellow, Gerald B.Organometallic vapor phase epitaxial growth of AlGaInPAlx Ga,, In, _ x _ y P with x + y = 0.51, lattice matched to the GaAs substrate, has been grown by organometaUic vapor phase epitaxy. The simple, horizontal, IR heated system operates at atmospheric pressure using the reactants TMA1, TMGa, TMln, PH3, and K2. Alloys giving room temperature, band edge...Liquid phase epitaxial growth; LPE; Alloys; Surface morphology1985
20 Mathews, V. JohnAn efficient algorithm for lattice filter/predictorABSTRACT An efficient method for updating the lattice filter/predictor coefficients using the sign algorithm is introduced. The pertinent coefficients are updated using only the signs of the estimation errors at each stage. This method requires less number of multiplications than other adaptive la...1985
21 Mathews, V. JohnAnalysis of the short-time unbiased spectrum estimation algorithmAbstract- The short-time unbiased spectrum estimation (STUSE) algorithm is analyzed and expressions for the mean and variance of the spectrum estimates are derived. The STUSE algorithm deliberately adds biased spectrum estimates in order to yield unbiased estimates and at the same time have excellen...1985
22 Stringfellow, Gerald B.GaInAsSb metastable alloys grown by organometallic vapor phase epitaxyGa1-xlnx As1-ySby alloys have been grown by organometallic vapor phase epitaxy using trimethyl compounds of Ga, In, As, and Sb(TMGa, TMIn, TMAs, and TMSb) plus AsH3 in an atmospheric pressure, horizontal, infrared heated reactor. For the first time, alloys near the center of the region of solid immi...Organometallic; Alloys; Vapor phase epitaxy1986
23 Stringfellow, Gerald B.Doping studies of Ga0.5In0.5P organometallic vapor-phase epitaxyPresents doping studies of gallium[sub0.5] indium[sub0.5] phosphorus organometallic vapor-phase epitaxy. Distribution coefficient of indium; Description of growth conditions; Case of poor growth morphology for gallium[sub0.5] indium[sub0.5] phosphorus.Phosphorus; Gallium; Doping1986
24 Mathews, V. JohnA unified approach to nonparametric spectrum estimation algorithmsAbstract-Different approaches to spectrum estimation can be broadly classified as parametric and nonparametric methods. In the parametric techniques, an underlying model is assumed in the formulation of the spectrum estimation problem and one estimates the parameters of the model. For nonparametric...1987
25 Mathews, V. JohnPredictive vector quantization of images using a constrained two-dimensional autoregressive predictorA novel approach to image compression using vector quantization of linear (one-step) prediction errors is presented in this paper. In order to minimize the image reconstruction error, we choose the optimum predictor coefficients (in a least-squares sense) that satisfy the additional constraint that ...1987
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