Advanced buffers for AlGaN/GaN HEMT and InGaN/GaN MQW on silicon substrates

Abstract

GaN growth was carried out on silicon (Si) substrates by metalorganic vapor phase epitaxy (MOVPE). A layer structure starting with HT (high-temperature) AlN and containing AlGaN and GaN as interlayers was employed for the subsequent deposition of GaN buffer layers. At first, the influence of the in-situ Al pre-deposition at the process start with different durations was investigated. Each time, the pre-deposition was followed by the same layer sequence and with thin AlGaN and GaN grown on top to form a high electron mobility transistor (HEMT). A significant enhancement could be observed in the properties of the investigated samples by reducing the pre-deposition time from 8 s to 2 s. Based on these results, multiple quantum well structures (MQW) and HEMT were grown on these buffers. For the MQW, the well thickness was increased and a shift to higher wavelengths was observed. The HEMT structures have shown enhanced properties by optimizing the growth temperatures of the top AlGaN layer.

Growth of GaN/AlGaN on 200 mm diameter silicon (111) wafers by MOCVD

“…The radius of curvature was measured as 43 m, which compares well with that reported on smaller wafers, e.g. [3,7], but results in a height from a level plane of 116 μm significantly greater than the 65 μm that would be observed on a 150 mm diameter wafer with the same radius of curvature.…”