Determination of photoluminescence mechanism in InGaN quantum wells

We report on the unambiguous experimental determination of the photolumines cence mechanism in a set of In0.25Ga0.75N quantum wells. Instead of studyin g the photoluminescence for different In contents, we have investigated it as a function of the quantum well width in combination with a similar study performed on GaN quantum wells. In this way, we show that the photolumines cence is not coming from quantum dots or very localized states in the quant um well, but from the quantum well itself under the influence of a piezoele ctric field induced by strain. The previously reported abnormal photolumine scence shifts and temperature dependencies can thus be explained. (C) 1999 American Institute of Physics. [S0003-6951(99)00241-7].