| The group-III nitride semiconductor alloys AlN-GaN-InN are recognized as an important material system for optoelectronic devices in the spectral range from infrared to ultraviolet. This thesis will investigate the carrier relaxation and carrier transport dynamics in InGaN, which are important for high speed device design.; Time-resolved pump-probe measurement is used to study carrier relaxation dynamics in an InGaN multiple-quantum-well (MQW) laser diode. Using the optical selection rule in InGaN, different subbands can be selectively pumped and probed using ultrafast optical pulse with different polarization. An ultrafast intersubband relaxation process (tau <0.35 ps) is found to be important to carrier dynamics in InGaN.; A novel heterodyne transient grating measurement is developed and used to study the carrier transport dynamics in InGaN. The measured diffusion constant is very small (∼0.2 cm2/s), indicate that carrier localization plays an important role in the carrier transport in InGaN MQWs. A simple model is presented to explain the measurement result. |
