HIGH-PURITY GAAS AND ALGAAS GROWN USING TERTIARYBUTYLARSINE, TRIMETHYLALUMINUM, AND TRIMETHYLGALLIUM

We have grown high purity AlGaAs by metalorganic chemical vapor deposi tion using tertiarybutylarsine (TEA), trimethylgallium, and trimethyla luminum. We have achieved p-type carrier concentrations less than 4 x 10(14) cm(-3) and a mobility of 1015 cm(2)/V . s at 77 K. Photolumines cence measurements at 4 K yielded bound exciton linewidths as narrow a s 4.3 meV, the narrowest reported linewidths for AlGaAs grown using TE A. Secondary ion mass spectrometry measurements found C, O, Si, and S concentrations below the instrument detection limits. A two level fact orial design was used to investigate the effects of temperature, V/III ratio, and group III partial pressure on the mobility, carrier concen tration, and growth rate. High V/III ratios at temperatures between 64 0-700 degrees C gave the highest quality material. Increasing the V/II I ratio caused a decrease in the growth rates of both GaAs and AlGaAs using either arsine or TEA. This dependence can be explained by a comp etitive adsorption model where excess group V species complete with gr oup III atoms for group III surface sites.