Electron transport in a coupled GaN/AlN/GaN channel of nitride HFET

Longitudinal hot-electron transport is investigated for the alloy-free AlGaN/AlN/{GaN/AlN/GaN} heterostructure at electric fields up to 380 kV/cm. The structure featured a coupled channel with a camelback electron density profile. The hot-electron drift velocity in the coupled channel is estimated as ~1.5×107 cm/s and is ~50% higher as compared with the standard AlN-spacer GaN 2DEG channel. The HFET with the pristine 2DEG density of 1.75×1013 cm–2 confined in the coupled channel demonstrates the optimal frequency performance in terms of electron velocity at a relatively low gate bias of VGS = –1.75 V. These results are consistent with the ultra-fast decay of hot phonons.