Crucial influential factor on background electron concentration in semi-polar (11[formula omitted]2) plane AlGaN epi-layers

Abstract

The semi-polar (112¯2) plane Al0.3Ga0.7N epi-layers with different background electron concentrations were deposited on (101¯0) m-plane sapphire substrates with metal-organic chemical vapor deposition technology, and characterized with Hall effect measurement, photoluminescence spectroscopy, high-resolution X-ray diffraction, and atomic force microscopy. It was found that there is a strong positive correlation between the background electron concentrations and the anisotropy in two-dimensional (2D)-growth rate of the triangular structures on the surface of semi-polar Al0.3Ga0.7N epi-layers. That is to say, the anisotropy in the 2D-growth rate is indeed the crucial influential factor on the background electron concentration. In fact, by carefully suppressing the anisotropy in 2D-growth rate, the background electron concentration in semi-polar Al0.3Ga0.7N epi-layers was reduced successfully from 1.38×1019 cm−3 to 4.20×1015 cm−3. This work should open a new way to realize the p-type semi-polar AlGaN epi-layers, which is of great significance for the manufacturing of semi-polar AlGaN-based DUV-LEDs.