Contributions to the science and technology of enhancing the internal quantum efficiency of nitride light emitting diodes

Light emitting diodes (LEDs) based on the (Al, Ga, In)N have enormous potential in improving current lighting and display technologies. Although nitride LEDs have shown remarkable improvement in output powers and efficiencies over the past 15 years, they are still limited by an efficiency "droop." Theoretical and experimental experiments suggest Auger recombination is the dominant cause to the efficiency droop. However, at very large current densities, Auger recombination alone cannot explain the drop in quantum efficiency. The efficiency droop can be mitigated by using thicker wells to reduce carrier densities in the active region. This has sparked interest in non-polar and semi-polar GaN. Recently, non-polar LEDs have been demonstrated to have output powers and efficiencies that rival c-plane devices. The best non-polar LEDs have relied on bulk substrates, which are expensive and small, which may limit their potential.;This thesis addresses the efficiency droop by investigating an alternative to bulk GaN substrates for non-polar LEDs and a hole trap that may be further decrease efficiency at large current densities. First, the cost of minimizing Auger recombination can be reduced by using an inexpensive substrate. This led to the development of a sidewall LED that featured an InGaN non-polar active region that used a sapphire substrate. The active regions were regrown on the sidewalls of stripes that had been etched into a N-polar GaN template.;Second, an interface trap was investigated at the InGaN/GaN interface with net negative polarization. A InGaN HEMT was designed so the interface trap would donate its electrons to the 2DEG. Current deep level spectroscopy measurements on the InGaN HEMT revealed a donor-like trap at the net negative InGaN/GaN interface. The density of the trap was measured using a UV-capacitance technique and charge neutrality. The location and density of the trap suggest it could increase the amount of non-radiative recombination at large current densities, which would in turn reduce internal quantum efficiency.