Lateral Carrier Diffusion In InGaN Quantum-wells

We report on the observation of carrier-diddusion-induced emission at high excitation density in a-plane InGaN/GaN multiple quantum wells. When increasing excitation density in a relatively high regime, we observed the emergence of defect-related emission band together with a significant reduction of bandedge emission efficiency. The experimental results are explainable with the carrier loss induced by density-actived carrier diffusion from localized states to defect states. Such a scenario, as comfirmed by the dependences of photoluminescence on the excitation photon energy and temperature, is a plausible origin of efficiency droop in a-plane light-emitting diodes. Finally, we propose a scheme on producing the InGaN nanorod, and through experiment we prove that this structure can effectively delay the efficiency droop in InGaN.The thesis is organized as following. Chapter 1 introduces a general review of the history and challenges of InGaN LEDs as well as the purpose of our research; In Chapter 2, the details of samples and experiments are described; Chapter 3presents our new findings about the cause of efficiency droop; Chapter 4 presents and tests our solvent of efficiency droop; Chapter 5 is a brief summary and outlook.