Influence of Si doping on characteristics of InGaN/GaN multiple quantum wells

We have systematically studied the influence of Si doping on the characteristics of InGaN/GaN multiple quantum wells (MQWs) by means of high-resolution x-ray diffraction (HRXRD), photoluminescence (PL), PL excitation (PLE), and time-resolved PL spectroscopy. The twelve period MQWs were grown by metalorganic chemical vapor deposition. Si doping in the GaN barriers was varied from 1 X 10(17) to 3 X 10(19) cm(-1). Information on the structural quality of the MQWs as a function of Si doping was extracted from the linewidth broadening of the higher-order superlattice satellite peaks measured in HRXRD. The HRXRD measurements indicate that increased Si doping results in better interface properties of the MQWs. PL and PLE measurements show a decrease in the Stokes shift with increasing Si doping concentration. The 10 K radiative recombination lifetime was observed to decrease from similar to 30 ns (for n < 1 x 10(17) cm(-3)) to similar to 4 ns (for n = 3 x 10(19) cm(-3)) with increasing Si doping concentration. The reduced Stokes shift, the decrease in radiative recombination lifetime, and the increase in the interface quality indicate that Si doping results in a decrease in carrier localization at potential fluctuations in the InGaN active layers. (C) 1998 American Institute of Physics. [S0003-6951(98)00434-3]