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We have grown dilute InPN layers by liquid phase epitaxy and characterized them using high resolution x-ray diffraction, optical absorption, low temperature photoluminescence, and Hall measurement techniques. Our results indicate that a maximum amount of 0.2% nitrogen has been incorporated in the material with a band gap lowering consistent with expectations. The crystalline quality of the material is found to improve upon nitrogen incorporation. Large increase in luminescence from the material is observed after a high temperature annealing. [ABSTRACT FROM AUTHOR]

The evolution of InAs quantum dots grown on InP substrates by metal-organic vapor phase epitaxy is studied as a function of InAs coverage. Under specific growth conditions, the onset of the two- to three-dimensional transition proceeds via two distinct pathways: through (i) an abrupt appearance of quantum dots as expected in the usual Stranski-Krastanov growth picture and (ii) a continuous evolution of small surface features into well-developed quantum dots. The average size of the features in both these families increases with coverage, leading to a bimodal distribution in dot sizes at an intermediate stage of growth evolution. On further deposition of material, the two families merge into a single broad unimodal distribution of sizes. Complementary information obtained from independent measurements of photoluminescence spectra and surface morphology is correlated and is found to be independently consistent with the picture of growth proposed. [ABSTRACT FROM AUTHOR]

The growth of InAsxSb1-x/GaAs (x<=0.06) heterostructures has been achieved using liquid phase epitaxy. High resolution x-ray diffraction studies reveal that the films are single crystalline and structurally coherent with the substrate. It is also inferred from these measurements that the in-plane and out-of-plane strain arising out of mismatched epitaxy is almost completely relaxed, leading to a high dislocation density. The room temperature energy gap is measured to be 0.13 eV for InAs0.06Sb0.94/GaAs. Temperature dependence of the energy gap is studied between 93 and 433 K through the absorption spectra. Temperature dependent Hall and mobility measurements carried out between 10 and 370 K on these samples are discussed. [ABSTRACT FROM AUTHOR]

InGaAs strained quantum well (SQW) samples with lattice matched InGaAsP quaternary barriers are grown on GaAs substrates by metalorganic vapor phase epitaxy. These SQW samples are characterized using photoluminescence, photomodulated reflectance, surface photovoltage spectroscopy and high-resolution x-ray diffraction techniques. The results based on numerical calculations are used to identify the various transitions seen in the spectra. The effect of growth temperature on the indium content of the InGaAs SQW with lattice matched InGaAsP quaternary barriers is studied. Contrary to the reported higher value of indium incorporation in InGaAs SQW with GaAs (In-free) barriers when the growth is performed at low temperatures, we find that the indium content of the InGaAs SQW with InGaAsP (In-based) quaternary barriers decreases if the SQW is grown at lower growth temperatures. A possible explanation for this behavior is provided. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Single crystal (100) wafers of n-InSb were implanted with 50 MeV Li3+ ions at various influences ranging from 10 to 10 ions/cm at room temperature. Investigations of the optical, electrical, and structural properties of the as-grown, irradiated, annealed wafers were carried out by infrared and Raman spectroscopies, Hall measurements, and high resolution x-ray diffraction (HRXRD). In the case of samples irradiated with an ion fluence of 1.610 ions/cm, electrical measurements at 80 K reveal that there is a decrease in carrier concentration from 8.510 (for unirradiated) to 1.1 10/cm and an increase in mobility from 5.4104 to 1.6710 cm/V s. The change in carrier concentration is attributed to the creation of electron trap centers induced by ion beam irradiation and the increase in mobility to the formation of electrical inactive complexes. Nevertheless, even with the irradiation at 1.610 ions/cm fluence the crystalline quality remains largely unaffected, as is seen from HRXRD and Raman studies. c 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents information on a study which used positron annihilation spectroscopy in evaluating strain relaxation and some defects in metals, alloys and semiconductors. Experimental details; Results and discussion; Conclusions.

Presents information on a study which focused on the Ga-In-P based self-organized quantum dot like structures formed during growth of short period superlattices sandwiched between GaInP alloy layers grown on gallium arsenide substrates. Experimental details; Results and discussion; Conclusions.

We report the observation of oscillatory features (OFs) in the photoreflectance (PR) and contactless electroreflectance (CER) spectra of CdTe films grown on Si substrate, at energies below the band gap of CdTe. The simultaneous observation of OF in the reflectance (R) spectrum having the same period as those in the PR and CER spectra (as also their dependence on film thickness) provides a direct proof for optical interference effects as being the source of these features. However, in the present case the amplitude of the OF gets damped towards shorter wavelengths while remaining nearly wavelength independent in the longer wavelength region indicating a modulation mechanism different from those reported earlier. A series of experiments and simulations performed by us seem to indicate that while in PR the principal mechanism is the pump beam induced periodic temperature changes which in turn modulates the optical path length of the CdTe film, in CER the mechanism is the electric field induced modulation of the subband gap refractive index of the film through the electro-optic effect. The damping of the OF has been explained on the basis of subband gap absorption by the CdTe film. © 1997 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Deals with a study which examined the photoreflectance and photoluminescence spectroscopy of low-temperature gallium arsenide grown by molecular-beam epitaxy. Information on modulation-doped photodectector structures; Methodology of the study; Results and discussion.

Describes deep-level transient charge spectroscopy (QDLTS) of tin donors in Al[subx]G[sub1-x]As. Characteristics of the QDLTS; Advantages of the QDLTS technique; Factors which possibly contribute to band structure and configuration effects.

Presents a study that introduced an Urbach tail in the absorption spectra of In[sub0.72]Ga[sub0.28]As[sub0.60]P[sub0.40] by germanium (Ge) doping. Semilog plots of the absorption coefficient for samples containing increasing amounts of Ge; Features of the spectra; Types of disorders that produce band tailing.

Discusses the transport properties of high energy 120Sn implanted GaAs and the effect of annealing on the electrical properties of the implanted layer. Formation of two layers at depth of 8.7 and 11 micrometers from the surface of the substrate; Fabrication of Schottky diodes on the implanted substrates; Presence of high series resistance due to radiation defects.

Presents a study which demonstrated the usefulness of a low-frequency capacitance deep level transient spectroscopy technique for samples with resistance in series with the depletion capacitance. Effects of series resistance from the contact resistance of aluminum gallium arsenide epitaxial layers; Errors in the density and activation energy of traps; Advantages of the low frequency technique.

Observes the thermal degradation of indium-phosphorus in open tube processing. Experimental techniques; Details on the data analysis techniques; Conclusions.

Presents a study that examined the DX centers in tin-doped aluminum-gallium arsenide using deep-level admittance spectroscopy (DLAS). Methodology; Analysis of the capacitance and conductance of the samples; Evaluation of the DLAS activation energy plots of the samples.

Examines the temperature dependence of forward and reverse currents of a-Si:Ge:H-Pd alloy Schottky barriers. Diode quality factor; Current voltage measurements; Capacitance measurements.

Presents information on a study which determined the band offset of a strained-layer single quantum well by a capacitance-voltage technique. Methods; Results; Discussion.