
55AlGaN/GaN High-Electron-Mobility Transistors
resistivity can be the replacement of GaN in the buffer with a larger bandgap mate-
rial such as AlGaN. However, the growth of such a layer on silicon is more difcult
due to the smaller lattice parameter of AlGaN and the resulting stress. Nevertheless,
we succeeded in growing up to 1.5-µm crack-free AlGaN with 5%–10% of Al and
with low crystal quality degradation [25,27]. This enables us to achieve more stable
drain leakage currents below 30 µA at V
ds
= 100V in the studied devices.
These devices are not passivated, so they are not able to sustain large drain and
gate biases. In spite of a drain lea ...