Influence of substrate miscut angle on surface morphology and luminescence properties of AlGaN

Gunnar Kusch,Paul R Edwards,Haoning Li,Thomas C Sadler,Jochen Bruckbauer,Peter J Parbrook,Robert W Martin

doi:10.1063/1.4867165

Gunnar Kusch, Paul R Edwards + Show 5 more

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https://doi.org/10.1063/1.4867165

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Abstract

The influence of substrate miscut on Al0.5Ga0.5 N layers was investigated using cathodoluminescence (CL) hyperspectral imaging and secondary electron imaging in an environmental scanning electron microscope. The samples were also characterized using atomic force microscopy and high resolution X-ray diffraction. It was found that small changes in substrate miscut have a strong influence on the morphology and luminescence properties of the AlGaN layers. Two different types are resolved. For low miscut angle, a crack-free morphology consisting of randomly sized domains is observed, between which there are notable shifts in the AlGaN near band edge emission energy. For high miscut angle, a morphology with step bunches and compositional inhomogeneities along the step bunches, evidenced by an additional CL peak along the step bunches, are observed.

Highlights

Obtaining optical information of wide band gap semiconductors is a challenging task
A crack-free morphology consisting of randomly sized domains is observed, between which there are notable shifts in the AlGaN near band edge emission energy
Using cathodoluminescence (CL) in a secondary electron microscope (SEM) enables information to be obtained on the surface morphology and the optical properties at the same time, allowing the two properties to be correlated

Summary

Introduction

Obtaining optical information of wide band gap semiconductors is a challenging task. While this has been done by photoluminescence (PL), using 193 nm or 244 nm lasers, the spatial resolution of PL is too low to investigate submicron surface features. Influence of substrate miscut angle on surface morphology and luminescence properties of AlGaN It was found that small changes in substrate miscut have a strong influence on the morphology and luminescence properties of the AlGaN layers.

Results

Conclusion