Germanium doping of gallium arsenide grown by molecular beam epitaxy — Some thermodynamic aspects

Abstract

A recent point defect model for GaAs, developed by Hurle to explain results from vapour phase and liquid phase epitaxy, has been extrapolated to apply to molecular beam epitaxy (MBE). Particular attention has been paid to the amphoteric doping obtained using Ge in MBE growth of GaAs. This thermodynamic treatment is shown to explain all the major features of recent experimental results. Thus, despite important non-equilibrium aspects of MBE growth, it appears that equilibrium thermodynamics can be used as a satisfactory guide to majority carrier dopant behaviour even in this complex case. An important supplementary result of the treatment is that As 2 should be a preferable source of arsenic to As 4 in MBE growth of GaAs.