Applied Physics Letters · 2015 · 93 citations · 22 references
EngineeringMaterials EngineeringMaterials ScienceElectronic MaterialsSemiconductor DevicesSurface ScienceEtching ProcessesIii-v SemiconductorsLight-emitting DiodesSemiconductor Device MaterialsSemiconductor SurfacesThin Film EtchingEtch ChemistryExtraction EfficiencyLight ExtractionLight Extraction EfficiencySelective EtchingSelectivityWet Chemical EtchingWet Etching
A controllable and smooth potassium hydroxide-based wet etching technique was developed for the AlGaN system. High selectivity between AlN and AlxGa1−xN (up to 12×) was found to be critical in achieving effective substrate thinning or removal for AlGaN-based deep ultraviolet light emitting diodes, thus increasing light extraction efficiency. The mechanism of high selectivity of AlGaN as a function of Al composition can be explained as related to the formation and dissolution of oxide/hydroxide on top of N-polar surface. Cross-sectional transmission electron microscopic analysis served as ultimate proof that these hillocks were not related to underlying threading dislocations.
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