Optical polarization properties of (11-22) semi-polar InGaN LEDs with a wide spectral range.

ABSTRACT: Electroluminescence polarization measurements have been performed on a series of semi-polar InGaN light emitting diodes (LEDs) grown on semi-polar (11-22) templates with a high crystal quality. The emission wavelengths of these LEDs cover a wide spectral region from 443 to 555?nm. A systematic study has been carried out in order to investigate the influence of both indium content and injection current on polarization properties, where a clear polarization switching at approximately 470?nm has been observed. The shortest wavelength LED (443?nm) exhibits a positive 0.15 polarization degree, while the longest wavelength LED (555?nm) shows a negative -0.33 polarization degree. All the longer wavelength LEDs with an emission wavelength above 470?nm exhibit negative polarization degrees, and they further demonstrate that the dependence of polarization degree on injection current enhances with increasing emission wavelength. Moreover, the absolute value of the polarization degree decreases with increasing injection current. In contrast, the polarization degree of the 443?nm blue LED remains constant with changing injection current. This discrepancy can be attributed to a significant difference in the density of states (DOS) of the valence subbands.

SUBMITTER: Poyiatzis N 

PROVIDER: S-EPMC7188879 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature