Transparent p-type layer with highly reflective Rh/Al p-type electrodes for improving the performance of AlGaN-based deep-ultraviolet light-emitting diodes

Abstract

Improving the light extraction of AlGaN-based deep-ultraviolet light-emitting diodes (DUV-LEDs) is attempted by introducing a highly transparent p-type layer together with reflective Rh/Al p-type electrodes. The p-GaN contact layer is thinned to balance the Ohmic contact and DUV light transmittance, which helps the Rh/Al p-type electrodes realize high reflection as well as good electrical performance. After optimization, the Rh/Al reflective p-type electrodes present reflectance of greater than 70% and specific contact resistivity of 3.75×10-4 Ω·cm2. Due to the improvement of the light extraction efficiency, the highest wall-plug efficiency (WPE) of 278 nm DUV-LEDs is improved by 57% compared to the conventional configuration with Ni/Au as the p-type electrodes.

A Review of Recent Research Advances on AlGaN-Based Deep Ultraviolet Light-Emitting Diodes

“…The maximum light output power and EQE of AlGaN-based DUV-LEDs with Ag nanodots/Al electrodes were increased by 52% and 58%, respectively, when compared with conventional Ni/Au electrodes at currents lower than 200 mA. Recently, Wang et al [95] replaced the Ag nanodot/Al reflective electrode with an Rh/Al reflective p-type electrode, which was optimized to have a reflectivity greater than 70% and a specific contact resistivity of 3.75×10 −4 •cm 2 . Due to the improvement in LEE, compared to the AlGaN-based DUV-LEDs with Ni/Au as a p-type electrode, the wavelength of 278 nm, the wall insertion efficiency of AlGaN-based DUV-LEDs is improved by 57%.…”