Process characterization and evaluation of hydride VPE grown Ga x In1−x As using a Ga/In alloy source

Abstract

A novel, simplified hydride vapor phase epitaxy (VPE) method based on the utilization of Ga/In alloys as the group III source was studied for deposition of GaxIn1-xAs. The effects of a wide range of experimental variables (i.e., inlet mole fractions of HC1 and AsH3, deposition temperature, gas velocity, Ga/ln alloy composition, and reactor geometry) on the ternary composition and growth rate were investigated. The growth rate of Ga x In1− xAs was found to increase with increasing deposition temperature and exhibited a maximum with inlet HC1 mole fraction. The growth rate increases slightly with inlet AsH3 mole fraction and is independent of gas velocity. The Ga composition of the deposited film increased with increasing inlet HC1 mole fraction and gas velocity. Increased In concentrations were observed with increases in inlet AsH3 mole fraction and deposition temperatures. Layers of Ga0.47In0.53As lattice matched to InP were successfully grown from alloys containing 5 to 8 at.% Ga. These layers were used to produce state-of-the-artp- i- n photodetectors having the following characteristics: dark current,I d(- 5 V) = 10-20 nA; responsivity,R = 0.84-0.86 A/W; capacitance,C = 0.88–0.92 pF; breakdown voltage,V b > 40 V. This study demonstrated for the first time that a simplified hydride VPE process with a Ga/ln alloy source is capable of producing device quality epitaxial layers.