Electrical and optical properties of thick highly doped p-type GaN layers grown by HVPE

摘要

In this paper we report 3-7 μm thick p-GaN growth by hydride vapor phase epitaxy (HVPE) on sapphire substrates. Mg impurity was used for doping. As-grown GaN layers had p-type conductivity with concentration N_A-N_D up to 3×10~(19) cm~(-3). Mg atom concentration was varied from 10~(17) to 10~(20) cm~(-3). Hydrogen concentration was about 10 times less than that for Mg, which may explain effective p-type doping for as-grownrnGaN layers. Micro-cathodoluminescence revealed a colum-nar-like structure of the GaN layers with a non-uniform distribution of material regions having dominant 362 nm or 430 nm luminescence. Use of these thick p-GaN layers to grow InGaN-based blue and green LEDs by the HVPE is demonstrated.