B. M. Arora

Luminescence spectra of an n‐channel metal‐oxide‐semiconductor field‐effect transistor at breakdown

Photon emission occurs from the drain gate boundary of a metal‐oxide‐semiconductor field‐effect transistor when drain bias exceeds the drain‐to‐source breakdown value. Spectral measurement of luminescence has been carried out over a wide range 0.7–3.1 eV in order to understand the origin of the emission. Three different types of detectors are used to measure the luminescence spectrum. A continuous broad spectrum is observed with a peak near 1.0 eV. The emission intensity decreases almost exponentially in the higher energy range.

Electroreflectance and surface photovoltage spectroscopies of semiconductor structures using an indium–tin–oxide-coated glass electrode in soft contact mode

Measurements of electroreflectance and surface photovoltage spectroscopy of semiconductor structures are described using a transparent indium–tin–oxide-coated glass electrode in soft contact mode on the semiconductor surface. This improvisation (simplification) reduces the magnitude of the ac modulation voltage necessary for the electroreflectance measurement to less than a volt from about a kV (∼103 V) as required in the conventional contactless setup. This soft contact mode also enhances the sensitivity of the surface photovoltage signal by three orders of magnitude. We also formulate an analytical criterion to extract the transition energies of a quantum well from the surface photovoltage spectrum.

Polarized photoluminescence and absorption in A-plane InN films

The authors report the observation of strong polarization anisotropy in the photoluminescence (PL) and the absorption spectra of [112¯0] oriented A-plane wurtzite InN films grown on R-plane (11¯02) sapphire substrates using molecular beam epitaxy. For A-plane films the c axis lies in the film plane. The PL signal collected along [112¯0] with electric vector E⊥c is more than three times larger than for E‖c. Both PL signals peak around 0.67eV at 10K. The absorption edge for E‖c is shifted to higher energy by 20meV relative to E⊥c. Optical polarization anisotropy in wurtzite nitrides originates from their valence band structure which can be significantly modified by strain in the film. The authors explain the observed polarization anisotropy by comparison with electronic band structure calculations that take into account anisotropic in-plane strain in the films. The results suggest that wurtzite InN has a narrow band gap close to 0.7eV at 10K.

Deep‐level transient charge spectroscopy of Sn donors in AlxGa1−xAs

Deep‐level transient charge spectroscopy (QDLTS) measurement is described. The technique is used to investigate energy levels of tin in AlxG1−xAs. The QLDTS spectra have multiple peaks which show the multilevel nature of the tin donors.

The role of hydrostatic stress in determining the bandgap of InN epilayers

This letter establishes a correlation between the internal stress in InN epilayers and their optical properties such as the measured absorption band edge and photoluminescence emission wavelength. By a careful evaluation of the lattice constants of InN epilayers grown on c-plane sapphire substrates under various conditions by metalorganic vapor phase epitaxy, the authors find that the films are under primarily hydrostatic strain. The corresponding stress results in a shift in the band edge to higher energy. The effect is significant and may be responsible for some of the variations in InN bandgap reported in the literature.

Long-wavelength photoluminescence from InGaP/GaAs heterointerfaces grown by metal organic vapour-phase epitaxy

Photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies are used to investigate the problems related to GaAs/InGaP/GaAs heterointerfaces grown by metal organic vapour-phase epitaxy (MOVPE). Normal PL features corresponding to the band gaps of GaAs and InGaP are seen for InGaP layer grown on GaAs. However, we observe an intense long-wavelength PL feature if we grow GaAs on InGaP while the features of InGaP and GaAs are suppressed. This PL feature varies significantly in wavelength with changes in the switching sequence and it could not be suppressed by the growth of a thin layer of GaP between InGaP and GaAs. Similar PL features are also observed for interrupted growth of InGaP on GaAs if we introduce AsH3 during the growth interruption. In this case, PLE measurements show that the corresponding PL features arise from an interfacial layer which is created during the interruption and lies sandwiched between the two halves of the InGaP layer. Thus, we show that a deleterious effect arises with the exposure of InGaP surface to AsH3 during the growth process with or without the Ga source and is attributed to the formation of an interfacial InGaAsP layer.

The capture cross-section and the Meyer-Neldel rule in III-V compound semiconductors

Abstract In this letter we show that the two signatures of a deep level — the capture cross-section and trap depth — are related to each other through the Meyer-Neldel rule. The physical mechanism responsible for this effect is not understood.

Studies on high resolution x-ray diffraction, optical and transport properties of InAsxSb1−x∕GaAs (x⩽0.06) heterostructure grown using liquid phase epitaxy

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 0.13eV for InAs0.06Sb0.94∕GaAs. Temperature dependence of the energy gap is studied between 93 and 433K through the absorption spectra. Temperature dependent Hall and mobility measurements carried out between 10 and 370K on these samples are discussed.

Growth of InSb epitaxial layers on GaAs (001) substrates by LPE and their characterizations

The growth of epitaxial InSb layers on highly lattice mismatched GaAs substrates has been successfully achieved via the traditional liquid phase epitaxy. Details about nucleation, growth and optimization have been dealt with. High-resolution X-ray diffraction studies on the epilayers reveal all reflections with distinct layer and substrate peaks even up to a highest scattering angle of 153°. However, the layer peaks are considerably broader, indicating extensive dislocations. The average dislocation density was estimated from the Full-width at half-maximum of symmetric reflection. The grown films were n-type and the typical value of the sheet carrier density at 80 K obtained for these samples was

High-mobility InSb epitaxial films grown on a GaAs (001) substrate using liquid-phase epitaxy

6.12\times10^{15}/cm^2