Optical investigation of InGaN/GaN multiple-quantum wells under high excitation

The emission mechanism of InGaN/GaN multiple-quantum wells (MQW) with different well thickness was analyzed, under high excitation. For the MWQs with wide well thickness, a strong emission from quantum-dot-like states was found, which was appeared only under high excitation on the high energy side of the emission from the transition between the first electron and first heavy-hole subbands. It was observed that the internal quantum efficiency was decreased with increasing temperature and dropped below 10% at room temperature, under low excitation. The results show that the emission mechanism under high excitation is found to be dominated by quantum-dot-like states from room temperature to low temperature.