Investigation of buffer growth temperatures for MOVPE of GaN on Si(1 1 1)

Abstract

GaN on Si(1 1 1) substrate was optimized employing an interlayer of low temperature (LT) AlN, high temperature (HT) GaN and another LT AlN layer. The first LT buffer layer was grown at 720°C on etched Si(1 1 1) substrates. In these experiments, we investigated the effects of the growth temperatures of the second LT buffer layer and the two HT buffer layers. The films were characterized by in-situ reflectance measurements, low temperature photoluminescence (PL) and sheet resistance measurements. Best results have been achieved using a growth temperature of 635°C for the second LT buffer layer and 1120°C for the HT buffer layers. A new crack evaluation method has been used to classify the grown structures. Up to 900 nm of crack-free GaN film with a smooth surface, low yellow PL band emission and high sheet resistance (3500 Ω/sq) were achieved on 2 inch Si. This GaN film is well-suited as the buffer for the subsequent deposition of high electron mobility transistors.