In-Situ generated arsine radicals for gallium arsenide homoepitaxy

Abstract

Removed from the deposition region, an upstream hydrogen microwave plasma generates arsenic hydrides by etching the surface of solid arsenic. The hydrides are transported to the deposition region and mixed with trimethylgallium to achieve low temperature (350°-400°C) and low pressure (750 mtorr) homoepitaxial GaAs films. Low precursor V:III ratios are used to achieve homoepitaxial films with high levels of carbon dopants (l0¹⁹ to mid 10²⁰ cm⁻³). No active or afterglow plasma exists in the growth region. The observed homo epitaxial growth activation energies of 54 kcal/mole and 66 kcal/mole for films deposited with V:III ratios of 1:1 and 1:4, respectively, are in the range of those reported for the heterogeneous decomposition of trimethylgallium in the absence of arsine. The films are found to be of good crystalline quality via double crystal x-ray rocking curves. The majority carriers are holes and have hole concentrations that correlate to the carbon doping, as determined by room temperature Hall effect measurements and secondary ion mass spectroscopy. Carrier mobility versus carbon concentration is also presented.