This work suggests new morphology for the AlGaN/GaN interface
which
enhances electron mobility in two-dimensional electron gas (2DEG)
of high-electron mobility transistor (HEMT) structures. The widely
used technology for the preparation of GaN channels in AlGaN/GaN HEMT
transistors is growth at a high temperature of around 1000 °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 °C in an N2 atmosphere
using TEGa as a precursor, the electron Hall mobility 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.