Deposition of GaN Layers with a lowered dislocation density by molecular-beam epitaxy

The deposition of a multilayer buffer layer that includes a high-temperature AlN layer grown at a temperature above 1100°C has made it possible to reduce the dislocation density in a GaN layer by 1.5–2 orders of magnitude to values in the range from 9 × 108 to 1 × 109 cm−2, compared with the case of growth on a thin low-temperature AlN nucleation layer. The decrease in the dislocation density causes a substantial increase in the electron mobility in the GaN layers to 600–650 cm2 V−1 s−1, which is in agreement with the results of calculations and is indicative of the high crystalline perfection of the layers.