LPE and VPE In<inf>1-x</inf>Ga<inf>x</inf>As<inf>y</inf>P<inf>1-y</inf>/InP: Transport properties, defects, and device considerations

Abstract

The electrical properties of In <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</inf> Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> As <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</inf> P <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-y</inf> alloys lattice matched to InP, grown by liquid-phase and vapor-phase epitaxial techniques, have been determined by various measurements. Several electron and hole traps, with activation energies varying from 0.26 to 0.82 eV, have been identified by transient capacitance and photocapacitance measurements and their density and capture cross section have been measured. The 0.82 electron trap has emission and capture properties identical to the dominant 0.83 eV electron trap present in bulk and VPE GaAs. Hall measurements were made on the alloys in the temperature range of 20-600 K. Analysis of the mobility data has yielded the values of several transport parameters including the alloy scattering potential <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Delta U</tex> as a function of composition. The maximum value of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Delta U \simeq 0.8</tex> eV corresponding to the bandgap <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E_{g} \simeq 0.95</tex> eV. Photo-Hall measurements at low temperatures show the presence of donor- and acceptor-like defects in the LPE and VPE alloys, respectively. These centers exhibit persistent photoconductivity at low temperatures and have a high barrier energy (∼0.2 eV) associated with electron capture. Defects, which are possibly located in the interconduction-valley region, have been identified from analysis of Hall data for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T &gt; 400</tex> K. The strong temperature dependence of the threshold current in injection lasers and the large leakage currents near breakdown in avalanche photodiodes have been discussed in the fight of the defects identified in the present investigation.