Investigation of Carbon Incorporation into GaAs by TEG_a-AsH₃ Based Low Pressure Metalorganic Chemical Vapor Deposition

Abstract

Heavily Carbon doped GaAs(l×1018−1×1020cm−3 ) grown by low pressure metalorganic chemical vapor deposition(LPMOCVD) using triethylgallium(TEGa), arsine(AsH3) as sources and liquid carbon-tetrachoride(CCI4) as dopant has been investigated. The carrier concentration was verified at various growth temperatures, V/III ratios and CCI4 flow rates. Dopant concentration first increased from 550°C and reached a maxium at 570°C and then decreased monotonously. Carbon incorporation was strongly enhanced when V/III ratio was less than 30 at Tg=590°C or less than 40 at Tg=630°C. Hole concentration increased and then decreased as CCI4 increased. The doping efficiency of epitaxtial layers grown on(100) substrate was higher than that on 2° off toward <110> misoriented substrate. Carbon doped GaAs films had higher Hall mobility than zinc doped GaAs films at high doping level due to less self-compensation. The highest dopant concentration in this system was 2.3×1020cm−3 at Tg=580°C and V/III=10.