The effect of rapid thermal annealing upon heavily Si-doped AlN/GaN quantum wells was demonstrated. After 1000C annealing for 5, 10 and 20min, the predominant effect was interdiffusion of Si rather than intermixing between the Al and Ga atoms. Both their original values and the magnitude of the changes after annealing revealed that inter-sub-band absorption and photovoltage were related to two different optical transitions as follows: absorption occurred in the 1 to 2 inter-sub-band transition, whereas photovoltage was due to a subsequent process from the 1 to 2 and the manifold of 2 to higher order transitions.

Si-Interdiffusion in Heavily Doped AlN-GaN-Based Quantum Well Intersubband Photodetectors. D.Hofstetter, J.Di Francesco, D.Martin, N.Grandjean, Y.Kotsar, E.Monroy: Applied Physics Letters, 2011, 98[24], 241101