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We present the design, fabrication, and demonstration of a 10/spl times/10 matrix-addressed vertical-cavity top-surface-emitting laser (VCSEL) array. These arrays are batch-fabricated from full 3-in diameter GaAs/AlGaAs wafers. We show that no performance-penalty is paid using top-contacted matrix addressed pixels over conventional planar VCSEL devices. A computer-controlled display system for electrically addressing the array was designed and constructed to permit video demonstration and array testing. >

Given two energy states (levels) in a quantum well formed by two potential barriers of finite thickness, elementary quantum mechanics tells us that the lower energy state is more tightly bound than the upper state. This produces a longer spatial confinement lifetime in the lower state than in the upper state. This ratio of lifetimes is opposite to that needed for laser action between these states. Furthermore, the lifetime of the lower energy state must be significantly shorter than the electron scattering time for the upper state. These facts have blocked the development of lasers based on these transitions. However, in this paper we report experimental and analytical results on a versatile type of semiconductor heterostructure that overcomes these difficulties. Unlike previous devices, this structure relies on an optical transition between two states which are both above-barrier quasibound states in the ‘classical’ continuum. The oscillator strength is large and the operation of the device clearly demonstrates coherent electron wave behavior. Such structures could represent the basis for a new room-temperature infrared semiconductor laser.

Responsivity and thermionic dark current are studied in asymmetric stepped GaAs/AlGaAs multiquantum well infrared detectors with a single bound state. Although attributed to different transport properties, both the photoexcited and the thermally emitted carriers exhibit asymmetric transport properties with respect to the voltage polarity. The experimental characteristics are explained by the minibands-quasi continuum energy structure above the barrier.

Compound semiconductors—semiconductors made when elements from Columns III and V of the Periodic Table are combined—are being used more frequently in the fabrication of integrated circuits. The evaluation and utilization of new processing technologies have enabled compound semiconductor technology to move out of the laboratory into real-world applications. Compound semiconductors, such as gallium arsenide and indium phosphide, are being used because of their inherent radiation hardness and their ability to quickly transmit electrons and because they can be utilized to make semiconductor lasers and photodetectors used in telecommunications. Although the raw chemical constituents used to make and process compound semiconductors have well-documented toxicological effects, compound semiconductor materials per se were not thought to present an acute toxicity hazard. This investigation documented the formation of arsine and phosphine—acutely toxic gaseous hydrides—which result from the handling and pro...

The transport of hot electrons in the AlxGa1−xAs barriers above the wells in a multiple quantum well (MQW) structure is investigated. The structures that are studied are asymmetric quantum well infrared detectors. The transport of the hot electrons normal to the layers is strongly dependent on both voltage and well shape. It is suggested that the key parameter which affects the transport properties is the dwell time of the electrons in the continuum, above the well region. This is most readily seen in asymmetric MQW structures, in which the dwell time under an applied bias depends very strongly on bias polarity. Calculations of electron transmission coefficient and dwell time show that the electron mean free path in asymmetric wells is much larger in positive bias than in a negative one. Employing this model, we achieve a very good fit to experimental data.

We introduce a new low-loss fast intracavity semiconductor Fabry-Perot saturable absorber operated at anti-resonance both to start and sustain stable mode locking of a cw-pumped Nd:YLF laser. We achieved a 3.3-ps pulse duration at a 220-MHz repetition rate. The average output power was 700 mW with 2 W of cw pump power from a Ti:sapphire laser. At pump powers of less than 1.6 W the laser self-Q switches and produces 4-ps pulses within a 1.4-micros Q-switched pulse at an approximately 150-kHz repetition rate determined by the relaxation oscillation of the Nd:YLF laser. Both modes of operation are stable. In terms of coupled-cavity mode locking, the intra-cavity antiresonant Fabry-Perot saturable absorber corresponds to monolithic resonant passive mode locking.

We have fabricated high power carbon‐doped InGaAs/AlGaAs lasers using an impurity‐induced layer disordering process to define the active region. The advantage of carbon doping is that it exhibits significantly lower diffusivity compared to other p‐type dopants, thereby avoiding displacement of the p‐n junction, even at the high temperatures and long diffusion times required by the disordering process. Secondary ion mass spectrometry (SIMS) measurements before and after Si diffusion show the p‐n junction position to be unchanged during processing. The carbon was introduced using CCl4 as an extrinsic precursor, giving improved control over doping levels and ternary growth conditions that is not available with intrinsic carbon doping. Thresholds of 20 mA and slope efficiencies of 0.44 mW/mA at 25 °C were obtained for lasers with cavity lengths of 500 μm and coated facets.

Vertical cavity zone lasers (Z-lasers) operating at 980 nm and 850 nm have been fabricated. This new class of high power (>100 mW) high efficiency (/spl eta//spl ap/ 36%) large area (70 /spl mu/m diameter) vertical cavity laser has an output that is automatically focused to a spot at a particular distance away from the laser. This is in contrast to the conventional surface or edge emitting array devices that usually have multiple far-field lobes and need external optical components for focusing purposes. Among other applications, the unique properties of 980 nm Z-lasers makes them attractive as a pump laser for fiber amplifier systems.

We report the observation of bistable polarization switching in a vertical‐cavity surface‐emitting laser under optical injection. The wavelength dependence of the switching is measured. It is found that this polarization switching is achieved through injection locking where both the wavelength and the polarization of the vertical‐cavity laser are locked to the injected optical signal.

Selectively excited room‐temperature photoluminescence spectra of InGaAs‐GaAs‐AlGaAs quantum well heterostructures reveal a broad line at midgap energies originating in the Si doped AlGaAs. When carriers are photoexcited directly in the wells, this line is dramatically enhanced at the expense of the quantum well line, indicating carriers escape from the wells. The broad emission and its enhancement can be explained in terms of recombination between electrons trapped at DX centers in AlGaAs and holes transferred into AlGaAs from the neighboring wells. We also observe the broad emission by direct over‐the‐gap photoexcitation of very highly doped Si:AlGaAs. The doping dependence consistently correlates this line to DX centers.

An asymmetric semiconductor electron wave Fabry–Perot interference filter has been designed with two above‐barrier quasibound states for optical transitions. The upper state was designed to have a spatial confinement lifetime greater than three times that of the lower state (which was designed to be less than 100 fs). Such lifetime ratios and magnitudes, which are nearly impossible for below‐barrier states, satisfy the criteria required for achieving population inversion. Furthermore, the transitions were designed to have large dipole matrix elements. Absorption measurements at multiple temperatures were used to demonstrate the first bound‐to‐quasibound transitions in an asymmetric structure. The experimental energies and dipole matrix elements are in agreement with calculated values. This type of structure could represent the basis for a new room‐temperature infrared semiconductor laser.

A new type of asymmetric stepped GaAs/AlGaAs multiquantum well infrared detector is reported. These asymmetric detectors utilize the usual bound‐to‐continuum transition. The current responsivity is remarkably asymmetric with regard to the voltage polarity. In contrast with rectangular wells, in which responsivity is saturated in both bias polarities, these wells exhibit saturation only for negative bias. The responsivity increases monotonously with positive electric field. This is attributed to changes induced by the field on the transport properties of the excited electrons. In particular, the bias affects the dwell time spent by the carrier wave packet in the well region. Employing this model, we achieve a very good fit with experimental data.

We demonstrate record high pulsed output power exceeding 530 mW from an electrically pumped phase‐coupled 8×8 vertical cavity surface emitting laser array (SELA) at room temperature. Three array types are compared: an 8×8 pixellated SELA(PSELA), an 8×8 grid contact SELA(CSELA), and a 78 μm×78 μm single broad area SEL(BSEL) emitter. The CSELA operating in a phase‐coupled supermode exhibits the lowest threshold current (100 mA) and voltage (1.6 V), highest damage threshold and a smooth L‐I characteristic with differential quantum efficiency ηd≳27%, the BSEL has the largest output power≳580 mW and a large ηd≳48%, the PSELA exhibited a large voltage with the largest ηd≳80%.

The effects of electrorefraction in quantum‐well Fabry–Perot (FP) modulators are discussed theoretically and illustrated experimentally. The large electrorefraction at the zero‐field heavy‐hole exciton is shown to produce strong modulation in FP devices operated at that wavelength. At longer operating wavelengths, the weakening electrorefraction plays a diminishing role. By taking into account the field dependent absorption α(λ,E) and dispersion n(λ,E) of the quantum‐well material, the measured reflectivity spectra are successfully modeled.

We find that GaAs‐AlGaAs quantum wells grown at low temperature (300 °C) by molecular beam epitaxy are nearly semi‐insulating and exhibit a broadened excitonic resonance. Studies of the femtosecond time‐resolved nonlinear optical saturation response and parallel‐field transport properties indicate that a subpicosecond nonradiative decay dominates the carrier recombination of this material. Annealing of low‐temperature‐grown quantum wells causes the arsenic point defects to form arsenic metallic precipitates within the quantum wells and up‐shifts the absorption edge.

Symmetric self‐electro‐optic effect devices (S‐SEEDs) using extremely shallow GaAs/Al0.04Ga0.96As multiple quantum wells are demonstrated. By exploiting mainly exciton ionization, rather than the usual quantum‐confined Stark shift, room‐temperature optical bistability is obtained with no applied bias. The extremely shallow symmetric‐SEED (symmetric E‐SEED) exhibits contrast ratios (CRs)≂3.5, with biasses

We have investigated the structural properties of Bragg reflectors grown by molecular beam epitaxy. The reflectors consist of quarter‐wavelength stacks of AlAs/ AlxGa1−xAs. We find a strong dependence of the interface quality on the substrate growth temperature, the Al composition in the ternary alloy, and the presence of impurities in AlAs. We have classified the interface disorder into two categories: interface roughness and structural waviness. We ascribe interface roughness to the segregation of oxygen during AlAs growth. The structural waviness originates from differing surface migration kinetics of Al and Ga which results in phase separation during growth of AlGaAs.

We have detected arsine with a toxic gas monitoring system during opening of an ultra high vacuum solid source molecular beam epitaxial system. The measured arsine concentration was in excess of 150 ppb. Our results are explained in terms of higher reactivity of arsenic species with water vapor after opening of the MBE chamber.

Hydrogen passivation of Si δ‐doped GaAs grown by molecular beam epitaxy is studied. Just as in uniformily Si‐doped GaAs, exposure of the δ‐doped material to a low frequency (30 kHz) hydrogen plasma at 250 °C for 30 min deactivates the Si donors in the δ spikes. For samples with Si doping of (1–6)×1018 cm−3, carrier concentration in the spikes decreased by nearly three orders of magnitude following hydrogenation. Secondary‐ion mass spectrometric analysis of deuterated samples confirmed trapping of deuterium in the Si‐doped spikes. Consistent with the deactivation of Si donors following hydrogenation, changes were observed in the near‐band edge luminescence spectrum at 4.2 K, which showed in the hydrogenated sample the absence of Burstein–Moss shift that was observed in the as‐grown sample. This hydrogen‐induced passivation of Si donors in the δ spikes can be of benefit in selectively deactivating donor atoms in device applications, and also provide a method for tailoring the hydrogen distribution in an epitaxial structure.

We have devised a novel vertical‐cavity top surface‐emitting GaAs quantum well laser structure which operates at 0.84 μm. The laser combines peripheral current injection with efficient heat removal and uses only the epitaxially grown semiconductor layers for the output mirrors. The structure is obtained by a patterned deep H+ implantation and anneal cycle which maintains surface conductivity while burying a high resistance layer. Peripheral injection of current occurs from the metallized contact area into the nonimplanted nonmetallized emission window. For 10‐μm‐diam emitting windows, ∼4 mA thresholds with continuous‐wave (cw) room‐temperature output powers ≳1.5 mW are obtained. Larger diameter emitting windows have maximum cw output powers greater than 3 mW. These are the highest cw powers achieved to date in current injected vertical‐cavity surface‐emitting lasers.

A possible laser device is designed with the use of classically free quasibound electron states. An asymmetric semiconductor electron wave Fabry-Perot interference filter is designed with an upper electron state having much stronger confinement than the lower electron state. This structure also allows for direct current pumping of the upper state and rapid depletion of the lower state under the presence of a field. Spectroscopy experiments demonstrate the existence of the upper quasibound state in a test structure. This laser filter structure, designed for infrared gain with current pumping, is combined with a special injector filter for room temperature narrow energy current injection into the upper lasing state. A stack of 54 periods of this electrically pumped structure is placed within a waveguide geometry. A laser device is fabricated by etching mesa structures from 50 to 100 micrometers wide. End cleaved facets serve as reflectors for mesas from 2 to 5 mm long. Tests are performed on these devices to determine their electrical properties and suitability for lasing.

A possible laser device is designed with the use of classically free quasibound electron states. An asymmetric semiconductor electron wave Fabry-Perot interference filter is designed with an upper electron state having much stronger confinement (235f6 lifetime) than the lower electron state (76f s lifetime). This structure also allows for direct current pumping of the upper state and rapid depletion of the lower state under the presence of a field. Experiments demonstrate the existence of the upper quasibound state in this structure. Another structure, designed for infrared gain with current pumping, has improved parameters over the structure used in the spectroscopy measurement.

We discuss the potential of using coherently-coupled vertical cavity surface emitting laser arrays ashigh-intensity light sources. In particular, the design and performance of a novel two-dimensional phase-coupled grid Contact vertical cavity Surface Emitting Laser Array (C-SELA) is reported. We discuss theoptical properties of the C-SELA; in addition to the usual out-of-phase array mode, we demonstrate in-phase SELA coupling. We introduce a simple physical model to describe our experimental results. Over 1.2Watt optical power emission is obtained at room temperature from an electrically-excited lOxlO C-SELA.This laser array exhibited a low threshold current density of only 600Amps/cm2 and over 60% single-endeddifferential quantum efficiency. I . INTRODUCTION High power semiconductor lasers have a number of important commercial, medical, and military appli-cations.1'2 To date, little research has been conducted into the potential of using Vertical Cavity SurfaceEmitting Lasers (VCSELs) as a high intensity light source. The advantages of using VCSELs for highpower include ease of manufacture and testing of 2D arrays and thus low cost production, good optical pro-perties, and a buried active region beneath a distributed mirror, low surface power density due to increasedemission area and hence, the potential for low catastophic optical damage. We have studied variousapproaches to achieving large coherent output power from VCSELs.3 These include using a broad-areaemission window, a closely-spaced individually-pixellated VCSEL array, and a novel approach using a gridcontact to force coherence across the array by modulating the gain and reflectivity. We demonstrated highcoherent optical output power exceeding 0.53 W in a single coherent supermode from an 8x8 phase-coupledpatterned grid Contact vertical cavity Surface Emitting Laser Array (C-SELA).3 The C-SELA exhibits asmooth L-I and a low-voltage (1 .6V threshold voltage) electrical characteristic overcoming some of themajor problems associated with VCSELs. Another similarly-sized 8x8 SELA was studied in which all ele-ments were individually pixellated. In contrast to the C-SELA, it was found that the pixelated SELA,although exhibiting an extremely large external quantUm efficiency rj

The complexity and size of interconnection-rich telephone switching systems require the extension of data buses over a large complement of frames. Physical designers have chosen bit serial transport over fiber to overcome the length limitations of coaxial cable from attenuation, to reduce cable volume, to provide isolation and avoid ground loops, to reduce RFI and EMI interference and coupling between channels, and to be able to make and break live connections without damaging the transmitter or receiver electronics. It has been shown that for certain interconnection applications there exists an optimum degree of parallelism (based on cost), depending on the data rate and the number of the channels.1 Prototype one-dimensional optical data links (1D-ODL’s) using linear 1 × n device arrays have been demonstrated in a number of laboratories and take advantage of the current infrastructure of fiber ribbon, splices, and connectors. Extending this concept to a second dimension by creating a two-dimensional optical data link (2D-ODL) using n×m device arrays may yield further economies of scale. We have constructed several prototype 2D-ODL’s (Table 1 ) using direct modulation of 2D arrays of vertical-cavity surface-emitting lasers (VCSEL’s)2 as shown in Fig. 1, and symmetric self-electro-optic effect device (S-SEED) modulators3 with Si P-I-N/bipolar OEIC receivers.4 The benefits and drawbacks of each technology will be briefly discussed.

An asymmetric GaAs/GaAlAs electron wave Fabry-Perot interference filter has been designed with two above-barrier quasi-bound states for infrared optical transitions.

A new type of asymmetric stepped GaAs/AlGaAs multi quantum well infrared detectors is reported. These asymmetric detectors utilize the usual bound to continuum transition. The current responsivity is remarkably asymmetric with regard to the voltage polarity. In contrast with rectangular wells, in which responsivity is saturated in both bias polarities, these wells exhibit saturation only for negative bias. The responsivity increases monotonously with positive electric field. The difference between polarities for the noise is much smaller at low temperatures. As a result, the highest D * in positive polarity is much higher than in the negative one. This is attributed to changes induced by the field on the transport properties of the excited electrons. In particular, the bias affects the dwell time spent by the carrier wave packet in the well region. Employing this model, we achieve a very good fit with experimental data. The transport asymmetry is further studied using identical asymmetric wells which were grown in opposite sequences. It is shown that the effect of the asymmetry in the interfaces is of the same order of magnitude as the structural asymmetry.

We report on Molecular Beam Epitaxial growth and properties of strained In0.2Ga0.8As-GaAs quantum well (QW) structures suitable for 980 nm lasers. The QW width was maintained at 80 A and the barrier thickness was varied from 50 A to 300 A. The effects of increasing the barrier width on the structural and optical properties of the QW were examined using double crystal x-ray diffraction rocking scans (DCXRD) and photoluminescence measurements. DCXRD rocking scans revealed satellite peaks from the strained layer quantum wells (SLQW). The linewidth of the peaks decreased as the barrier width was increased. Optical measurements indicate significant improvements in the internal luminescence efficiency in the thick barrier structures. We assign the improvements in the luminescence properties to the reduction of non-radiative centers in the thick barrier structures. The sources of the non-radiative centers are ascribed to structural defects that are generated as a result of strain relaxation in the thin barrier structures. A new broad photoluminescence feature at 0.9 eV was also observed and believed to originate in the AlGaAs:Si cladding region. We shall present these results and discuss the implications of increasing the barrier thickness of In0.2Ga0.8As-GaAs QW on the performance of 980 nm lasers.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We report batch-processed, totally planar, vertical-cavity top surface emitting GaAs/AlGaAs laser devices and arrays. Different size devices are studied experimentally. We measure continuous-wave threshold currents down to 1.7 mA and output powers > 3.7 mW at room temperature. We also discuss interesting characteristics such as differential quantum efficiencies exceeding unity and multi-transverse mode behavior. An array having 64 X 1 individually-accessed elements is characterized and shown to have uniform room-temperature continuous-wave operating characteristics in threshold current approximately equals 2.1 +/- 0.1 mA, wavelength approximately equals 849.4 +/- 0.8 nm, and output power approximately equals 0.5 +/- 0.1 mW.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Advances in epitaxial growth techniques such as molecular beam epitaxy and metal organic chemical vapor deposition have facilitated the formation of high quality III-V heterostructures with dimensional control down to atomic levels, with abrupt doping and near-defect-free interfaces. The flexibility and remarkable control offered by these techniques have resulted in the fabrication of new devices based on confinement or modulation of carriers in thin III-V heterostructures. Quantum wells and superlattice based devices are expected to be utilized in optical information processing as sources, modulators, and detectors. In this paper, we will review the general epitaxial requirements for quantum wells and superlattices based devices, and discuss the fabrication and properties of a new class of infrared photodetectors that employ intraband transitions in quantum wells.

We report on molecular beam epitaxial growth of Si doped, single and multiple quantum well structures. We have examined the effects of growth parameters such as substrate temperature, group V/III ratio, and intentional and unintentional impurities, on the electrical and optical properties of the quantum wells structures. Capacitance–voltage and secondary ion mass spectrometry analysis of the structures reveal that the net density of electrically active carriers in the wells is controlled by the number of acceptor states in the AlGaAs barrier. We have assigned the source of the acceptor state to the presence of oxygen in the AlGaAs barrier. We observe that the strength of the intersubband optical absorption from the quantum wells increases linearly with the Si‐doping in the well. Photoluminescence measurements indicate that for a given substrate temperature, a lower V/III ratio results in higher quality quantum well.

Hybrid mode locking of a broad-area semiconductor laser with a multiple-quantum-well saturable absorber in an external cavity is demonstrated. A novel method for mode control of the broad-area laser output, based on patterning of the multiple quantum well absorber into a microdot mirror structure, is presented. Pulses as short as 15 ps, at a repetition rate of 593 MHz, with an average power of 9 mW and a peak power of 1 W have been achieved.

Tho Letter reports the reduction of p-mirror electrical resistance using a very simple delta doping technique. The differentia] resistance was reduced almost by half, and the peak output power was increased by about 40% with delta doping. No significant difference was observed in threshold current and efficiency.

The Letter reports for the first time over 1 W pulsed optical power emission obtained at room temperature from an electrically-excited grid-contact vertical cavity top surface emitting laser array. This laser exhibited a low threshold current density of only 600 A/cm2 and over 60% single-ended differential quantum efficiency.

Kerr lens mode-locked (KLM) solid-state lasers are typically not self-starting. We address this problem by introducing a broadband semiconductor saturable absorber that could be used as a tunable, all-solid-state, passive starting mechanism. We extend the wavelength tunability of a semiconductor saturable absorber to more than 100 nm using a band-gap-engineered low-temperature molecular-beam-epitaxy (MBE)-grown bulk AlGaAs semiconductor saturable absorber in which the absorption edge of the saturable absorber has been artificially broadened by continuously reducing the Al concentration during the MBE growth. We demonstrate its tunability and its feasibility as a starting mechanism for KLM with a picosecond resonant passive mode-locked Ti:sapphire laser. The extension to femtosecond KLM lasers has been discussed previously.

Ion beam milling-induced damage in a 500 A AlGaAs/40 A GaAs/500 A AlGaAs single quantum well structure was investigated using low temperature cathodoluminescence spectroscopy. The ion beam energy (500-1500 eV) dependence of luminescence intensity indicated that minimum damage is introduced at a beam energy of 500 eV. Most (80-85%) of the original luminescence intensity was recovered on annealing at 400 o C for 5 min

Highly efficient (1.2 mW/mA, >70% CW differential quantum efficiency), top-surface-emitting, vertical cavity lasers are achieved at room temperature. Buried damage layers by proton implantation are used for efficient current funnelling. The CW threshold currents are 3.5–8.0 mA, at 3.7–4.2 V bias, for 10.30 μm diameter lasers. The lasing wavelengths are 845–848 nm.

We report a new photoluminescence defect spectrum with a no‐phonon transition at 1.0192 eV which emerges in many silicon layers grown on silicon substrates by molecular beam epitaxy. Comparison of the no‐phonon transition and the chief local mode (ℏω=7.5 meV) to the well‐established Cu‐related spectrum at 1.0145 eV suggests that the new defect incorporates Cu as well. Deep level transient measurements support the presence of Cu in the epilayers. We suggest that this defect spectrum has recently been observed by others but was not identified and associated with Cu.

Bulk GaAs grown by the Bridgman technique changes its electronic properties in response to heat treatment. These changes were studied by deep level transient spectroscopy, photoluminescence, and Hall effect measurements. We report the dependence of the conductivity changes on starting material composition, annealing temperature, and annealing duration. The changes are related to the stability of a shallow acceptor which is present in concentrations ≥1016 cm−3 and reflect the equilibration of native defects introduced during the crystal growth process. The implication of this study is that as‐grown GaAs is a metastable material with its ultimate electrical properties being determined by process conditions.

Deep level transient spectroscopy has been employed in a study of impurity‐interstitial defect reactions in silicon following room‐temperature electron irradiation. Three defects have been isolated and identified from their reactions and electrical properties as Cs‐Ci, Ci‐Oi, and Ps‐Ci. The Cs‐Ci, ME[(0.10), (0.17)] and Ps‐Ci, ME[(0.21), (0.23), (0.27), (0.30)] defects exhibit metastable structural transformations. Our results reveal the multistructural nature and chemical reactivity of the silicon self‐interstitial.

Expanding interest in large-scale fabrication of electronic and photonic devices and in the scale-up of epitoxial growth reactors is creating the need for high quality large diameter InP substrate material. This paper will discuss the evaluating of three-inch diameter semi-insulating Fe-doped InP substrate material purchased from two commercial suppliers. The results of Photon Back Scatter, Infrared Transmission Microscopy, Hall Effect, and Spatially Resolved Photoluminescence measurements will be presented and evaluated.

Changes in the electronic properties of bulk GaAs crystals, grown from melts of varied As:Ga ratios, and Si-donor concentrations, were investigated by annealing in the temperature range 850°C to 1050°C. We found a gradual reduction of the free carrier concentration, a corresponding decrease in the luminescence spectral intensity, and a suppression of the near band-edge peaks with annealing time at any temperature. Deep level and impurity concentrations remained essentially constant. The magnitude of these changes was found to be determined predominantly by the annealing time and temperature, and the starting composition of the material We argue for a non-radiative native acceptor defect, or defect complex, forming during the annealing cycle. We present here the thermodynamic interpretation for this behavioi in terms of point defect equilibria.

DLTS measurements are used to detect and identify the interstitial related defects in n-type silicon. The materials dependences of the reactions of the [E(0.12), H(O.27)], [ME(0.30), ME(0.29), ME(0.23), ME(0.21)], ]ME(0.10), ME(0.17)] and [H(0.36)] spectral features lead to their identification as representing the two charge states of Ci, the multistable configurations of Ps-Ci, the bistable Cs-Sii-Cs, and the Ci-Oi defects, respectively. The branching ratios for the reactions of interstitial carbon with the impurities are given.

We have grown homogeneous alloys of Sn1−xGex with 0.01