P-Type GaN Directly Grown by Low Pressure Metalorganic Vapor Phase Epitaxy

P-type GaN was grown on AI₃O₂ substrate by low pressure metalorganic vapor phase epitaxy without any post treatment. The p-type conduction of as-grown GaN has the typical characteristics of a light-doped or high-compensation semiconductor, that is a hole concentration of 2.2 x 10¹⁷cm^-3 at 77K, which changes to n-type with an electron concentration of 2.7 x 10¹⁷ cm^-3 at room temperature. After thermal annealing under a N₂ ambient, it showed the characteristics of a heavy-doped semiconductor and the hole concentration was enhanced reaching a hole concentrations of 4.2 x 10¹⁷ at 77K and 5.7 x 10¹⁷ cm^-3 at room temperature.