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

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 NA‐ND up to 3×1019 cm–3. Mg atom concentration was varied from 1017 to 1020 cm–3. Hydrogen concentration was about 10 times less than that for Mg, which may explain effective p‐type doping for as‐grown GaN layers. Micro‐cathodoluminescence revealed a columnar‐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. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)