The Bloch-Gruneisen mobility of two-dimensional electron gas in AlGaN/GaN heterostructures

We present calculations of the Bloch-Gruneisen electron mobility in zincblende (ZB) and wurtzite (WZ) AlGaN/GaN quantum-well heterostructures. Within the Boltzmann equation approach, we derive an expression for the momentum relaxation time which explicitly takes into account the Pauli principle restrictions, and show that these are comparable in importance to a screening effect at temperatures up to 150 K provided that the electron density is high. This is of particular importance for GaN-based quantum wells for which very high electron densities initiated by the strain-induced and spontaneous polarization fields have been recently reported. Dependences of the mobility on the lattice temperature and the electron density for both ZB and WZ GaN are presented, and it is shown that the WZ mobility is higher than the ZB mobility. (C) 1999 American Institute of Physics. [S0003-6951(99)02537-1].