Electron Transport Properties in High Electron Mobility Transistor Structures Improved by V-Pit Formation on the AlGaN/GaN Interface

This work suggests new morphology for the AlGaN/GaN interface which enhances electron mobility in two-dimensional electron gas (2DEG) of high-electron mobi l i t y transistor (HEMT) structures. The widely used technology for the preparation of GaN channels in AlGaN/GaN HEMT transistors is gro w t h at a high temperature of around 1000 degrees C in an H2 atmosphere. The main reason for these conditions is the aim to prepare an atomically flat epitaxial surface for the AlGaN/GaN interface and to achieve a layer with the lowest possible carbon concentration. In this work, we show that a smooth AlGaN/GaN interface is not necessary for high electron mobility in 2DEG. Surprisingly, when the high-temperature GaN channel layer is replaced by the layer grown at a temperature of 870 degrees C in an N2 atmosphere using TEGa as a precursor, the electron Hall mobi l i t y increases significantly. This unexpected behavior can be explained by a spatial separation of electrons by V-pits from the regions surrounding dislocation which contain increased concentration of point defects and impurities.