Influence Of Surface Preparation And I-Algan Thickness On Electrical Properties Of I-Algan/Gan Heterostructures

The influence of surface preparation and wet-etching of AlGaN layer on electrical properties of bare i-AlGaN/GaN and Ni/i-AlGaN/GaN Schottky samples has been investigated. Hall effect measurements of bare samples indicated that the surface oxide increases 2DEG density, while the thinner the AlGaN layer, the lower the 2DEG density is, accompanied with reduced electron mobility. Theoretical analysis indicated that the former is due to towering of the surface barrier, while in the latter the 2DEG density changes according to theoretical curve with a constant surface barrier. For Schottky samples, both forward and reverse currents increased with reducing the AlGaN layer, giving smaller effective Schottky barrier height (SBH). The behavior can be well explained by combined leakage currents due to leaky patches and simple tunneling through the surface barrier. (c) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.