Micro-photoluminescence analysis of semi- and non-polar nitrides: local efficiency and transport

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The experimental technique of micro-photoluminescence is used to study the optical properties of semi- and non-polar InGaN quantum wells (QWs) on a microscopic scale, in particular the influence of crystal orientation on sub-micrometer fluctuation of photoluminescence, electroluminescence, and photocurrent. These spatially resolved local measurements will be compared with global measurements of internal quantum efficiency (IQE) and time-resolved electroluminescence to investigate the mechanisms limiting quantum efficiency in InGaN QWs of different orientation. We recently demonstrated that the “time-of-flight” technique allows a quantitative measurement of carrier transport within the plane of the InGaN QW. This method will be used to measure the impact of the piezoelectric field on carrier drift and diffusion in semi- and non-polar QWs. The question of anisotropic carrier transport, i.e. drift, in the semi- or non-polar plane due to anisotropic carrier mobility and an in-plane component of the piezoelectric field will be addressed. On the device level we will continue with measurement and simulation of optical gain, waveguiding, and dynamic properties of semipolar laser diodes.