Dislocation-independent mobility in lattice-mismatched epitaxy: application to GaN

Lattice-mismatched epitaxy produces a high concentration of dislocations (Ndis) in the interface region, and this region is often highly conductive, due to donor (ND) decoration of the dislocations. Here we show that a simple postulate, ND=α(Ndis/c), where c is the lattice constant and α a constant of order 1–2, predicts a nearly constant low-temperature mobility, independent of Ndis. This prediction is experimentally verified in GaN grown on Al2O3, and is also applied to other mismatched systems.