CARBON INCORPORATION DURING GROWTH OF GAAS BY TEGA-ASH3 BASE LOW-PRESSURE METALORGANIC CHEMICAL-VAPOR-DEPOSITION

Heavily carbon-doped GaAs (1 X 10(18) approximately 1 X 10(20) cm-3) g rown by low-pressure metalorganic chemical vapor deposition using trie thylgallium and arsine as sources and liquid carbon-tetrachloride (CCl 4) as dopant has been investigated. The carrier concentration was veri fied at various growth temperatures, V/III ratios, and CC]4 flow rates . Dopant concentration first increased from 550-degrees-C and reached a maximum at 570-degrees-C growth temperature (T(g)) and then decrease d monotonously. Carbon incorporation was strongly enhanced when the V/ III ratio was less than 30 at T(g) = 590-degrees-C or less than 40 at T(g) = 630-degrees-C. Hole concentration increased and then decreased as CCl4 flow rate increased. Growth rate of layers decreased as growth temperature and flow rate Of CCl4 increased. The doping efficiency of epitaxial layers grown on the (100) substrate was higher than that on the 2-degrees off toward [110] misoriented substrate. Carbon-doped Ga As films had higher Hall mobility than zinc-doped GaAs films at high d oping levels due to less self-compensation. The highest dopant concent ration in this system was 2.3 X 10(20) cm-3 at T(g) = 580-degrees-C an d V/III = 10.