P-TYPE GAN DIRECTLY GROWN BY LOW-PRESSURE METALORGANIC VAPOR-PHASE EPITAXY

P-type GaN was grown on Al3O2 substrate by low pressure metalorganic v apor phase epitaxy without any post treatment. The p-type conduction o f as-grown GaN has the typical characteristics of a light-doped or hig h-compensation semiconductor, that is it hole concentration of 2.2 x 1 0(17) cm(-3) at 77K, which changes to n-type with an electron concentr ation of 2.7 x 10(17) cm(-3) at room temperature. After thermal anneal ing under a N-2 ambient, it showed the characteristics of a heavy-dope d semiconductor and the hole concentration was enhanced reaching a hol e concentrations of 4.2 x 10(17) cm(-3) at 77K and 5.7 x 10(17) cm(-3) at room temperature.