High-temperature stimulated emission in optically pumped InGaN/GaN multiquantum wells

Stimulated emission (SE) in optically pumped InGaN/GaN multiquantum well (MQW) structures grown by metalorganic chemical vapor deposition was experimentally studied in the temperature range of 175-575 K. The GaN barriers were intentionally doped with a different Si concentration ranging fr om 1 X 10(17) to 3 X 10(19) cm(-3) and the effects of Si doping of GaN barriers on the optical properties of InGaN/GaN MQWs were investigated. The SE threshold was measured as a function of temperature and compared with bulk GaN. We observed that the SE threshold had a low value and a weak temperature dependence: for example, similar to 25 kW/cm(2) at 175 K, similar to 55 kW/cm(2) at 300 K, and similar to 300 kW/cm(2) at 575 K for one of the samples. Low SE thresholds are attributed to the high-quantum efficiency of the MQWs, possibly associated with the large localization of excitons. The characteristic temperature of 162 K was derived from the temperature dependence of the SE threshold. The integrated emission intensity versus pumping density was examined for different temperatures. This study shows that InGaN/GaN MQWs are suitable for development of laser diodes that can operate well above room temperature. (C) 1998 American Institute of Physics.