InGaN-Based Light-Emitting Diodes with a Multiple-Air-Gap Layer

Abstract

InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) that have a multiple-air-gap (MAG) structure to increase light extraction efficiency and to reduce the piezoelectric field in an InGaN active layer are described. The LED structure was regrown on a GaN template layer that consists of the photoelectrochemical (PEC)-treated nanoporous GaN:Si layer with a bottom MAG structure and a top GaO x layer that acts as a self-assembled micromask for the epitaxial lateral overgrowth process. Electroluminescence (EL) spectra having a 5.0 nm blueshift phenomenon and a peak intensity of up to 52% enhancement in the MAG-LED compared to a standard light-emitting diode (ST-LED) at 20 mA operating current were obtained. The wavelength blueshift of the EL spectra, with an increasing injection current, in the MAG-LED (5.9 nm) was smaller than that in the ST-LED (8.1 nm). The wavelength blueshift of the micro-photoluminescence spectra, when varying the reverse-bias voltage from 0 to -13 V, was measured as 5.7 and 3.9 nm in the ST-LED and in the MAG-LED, respectively. A higher light extraction efficiency and a lower piezoelectric field in the InGaN wells were observed in the MAG-LED by inserting the PEC-treated MAG structure and a top GaO x layer.