Effects of compressive strain on optical properties of In xGa 1-xN/GaN quantum wells

N. Khan, J. Li

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Abstract

In0.2 Ga0.8 NGaN multiple quantum well (MQW) blue light emitting diode (LED) structure was grown on a specially designed sapphire substrate (with increasing thickness from the edge to the center within a single wafer). X-ray diffraction revealed that the GaN lattice constant c decreases continuously from the edge to the center, indicating a continuous variation in the compressive strain. The spectral peak positions of the electroluminescence (EL) spectra exhibited a blueshift when probed at the edge as compared to the center, which is a direct consequence of the continuous variation in the compressive strain across the wafer. Based on the experimental results, a ratio of elastic stiffness constants (C33 C13) for GaN was deduced to be ∼5.0±1.0, which was in agreement with the calculated value of ∼4.0. A linear relation of the EL emission peak position of LEDs with the biaxial strain was observed, and a linear coefficient of 19 meVGPa characterizing the relationship between the band gap energy and biaxial stress of In0.2 Ga0.8 NGaN MQWs was also obtained.

Original languageEnglish
Article number151916
JournalApplied Physics Letters
Volume89
Issue number15
DOIs
StatePublished - 2006

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