M. A. Pollack

Band gap versus composition and demonstration of Vegard’s law for In1−xGaxAsyP1−y lattice matched to InP

Measurements of lattice parameters and compositions for In1−xGaxAsyP1−y lattice matched to InP demonstrate the validity of Vegard’s law for this quaternary. The measured compositional dependence of the band gap shows a bowing parameter smaller than predicted from the previously measured band gaps of the four constituent ternaries.

The band structure dependence of impact ionization by hot carriers in semiconductors: GaAs

Abstract We present the first systematic study of the dependence of impact ionization by electrons and holes upon the details of the electronic band structure. Our measurements, made in GaAs, establish the crucial role of the ionization threshold energy, and its location in the Brillouin zone, in determining the ionization rates. This relationship is apparent in the dependence of impact ionization rates on the temperature of the lattice, compositional changes for the alloy GaAs 1- x Sb x , and the orientation and strength of the electric field. The strong dependence of impact ionization upon specific features of the electronic band structure is a new principle which can be used to study the nature of electronic states in a wide variety of semiconductors through hot-carrier behavior.

Growth and properties of liquid‐phase epitaxial GaAs1−xSbx

A detailed study is presented of the Ga‐As‐Sb ternary phase diagram. Liquidus temperatures have been measured between 700 and 900 °C by direct observation of the solutions, and layers then grown epitaxially on GaAs substrates. The nonequilibrium effect of constitutional supercooling on the compositions of the grown layers is investigated. Solidus compositions, from layers slowly grown to minimize this effect, are used together with the liquidus data to fit a calculated phase diagram. These results lead to the conclusion that GaAs1−xSbx is a borderline case between miscible and immiscible solid solutions. An accurate determination of the ternary band gap has been made as a function of composition over the range 0⩽x⩽0.2. The room‐temperature electrical properties of undoped, Te‐doped (n‐type), and Ge‐doped (p‐type) epilayers have also been determined.

Liquid phase epitaxial In1−xGaxAsyP1−y lattice matched to 〈100〉 InP over the complete wavelength range 0.92⩽λ⩽1.65 μm

A two‐phase supercooled solution method is described for the LPE growth of In1−xGaxAsyP1−y on 〈100〉 InP over the entire range of lattice‐matched compositions, 0⩾y<1, 0?x<0.47. Liquid and solid compositions, distribution coefficients, and band‐gap data which may be used to design specific devices are presented.

Liquid phase epitaxial Ga1-xInxAsySb1-y lattice-matched to (100) GaSb over the 1.71 to 2.33μm wavelength range

Measurements and calculations of the GaInAsSb phase diagram near 530°C are reported. Epitaxial growth of compositions lattice-matched to GaSb is demonstrated over the range 0 ≤ x ≲ 0.22 before encountering the expected miscibility gap. Photoluminescence measurements yield bandgap energies from 0.73 eV for GaSb down to 0.53 eV at x = 0.22, indicating the potential application of these materials for optoelectronic devices operating at wavelengths between 1.71μm and 2.33μm.

Lattice vibrations of In1−xGaxAsyP1−y quaternary compounds

We report a Raman study of the lattice vibrations of the quaternary compound In1−xGaxAsyP1−y over the whole range of compositions lattice‐matched to InP. The major bands in the spectra show a pseudo‐two‐mode behavior involving the optical phonons of InGaAs and InP. A low‐frequency structure is attributed to disorder‐induced scattering by acoustical vibrations. Weaker bands are assigned to Ga‐P and In‐As pair vibrations.

Continuous operation of 1.0‐μm‐wavelength GaAs1−xSbx/AlyGa1−yAs1−xSbx double‐heterostructure injection lasers at room temperature

Double‐heterostructure GaAs1−xSbx/AlyGa1−yAs1−xSbx injection lasers have been operated continuously at room temperature for the first time. Emission was near 1.0 μm. The lowest threshold current density observed was 2.1 kA  cm−2 dc.

High performance GaInAsSb/GaSb p‐n photodiodes for the 1.8–2.3 μm wavelength range

GaInAsSb/GaSb p‐n heterojunction photodiodes prepared by liquid phase epitaxy are described. The low net acceptor concentration obtained by Te compensation of the quaternary layer permits a room‐temperature external quantum efficiency of 67±5% to be achieved at a wavelength of 2.2 μm.

High‐efficiency In1−xGaxAsyP1−y/InP photodetectors with selective wavelength response between 0.9 and 1.7 μm

We report In1−xGaxAsyP1−y/InP photodiode detectors with external quantum efficiencies of 50–70% without antireflection coating. The short‐ and long‐wavelength response limits of these very efficient detectors can be compositionally tuned to lie anywhere in the wavelength range 0.9

Growth and characterization of liquid−phase epitaxial InxGa1−xAs

The liquid−phase epitaxial growth of InxGa1−xAs (0<x≲0.15) single and multiple layers on GaAs substrates has been studied. Growth on 111B−oriented substrates results in planar interfaces, although it requires careful control of the growth temperature relative to the liquidus temperature. For this reason, detailed liquidus and solidus data along the 850 °C isotherm have been determined for the In−rich corner of the In−Ga−As system. The phase diagram of the system has been calculated and found to be in satisfactory agreement with the measurements. An accurate determination of the room−temperature band gap of InxGa1−xAs as a function of x has been made using photoreflectance and photoluminescence techniques. The room−temperature electrical properties of doped layers also have been measured, and Zn acceptors and Se or Te donors were found to be useful dopants. Ge was found to be an amphoteric dopant; it is an acceptor for x≲0.07 and otherwise a donor. By making use of stepwise compositionally graded lattice−m...