Narrow-Linewidth GaN-on-Si Laser Diode with Slot Gratings.

Masao Ikeda,Tong Liu,Shuming Zhang,Jianxun Liu,Yaping Kong,Yongjun Tang,Zengli Huang,Meixin Feng,Hui Yang,Qian Sun,Xiujian Sun,Shizhao Fan

doi:10.3390/nano11113092

Abstract

This letter reports room-temperature electrically pumped narrow-linewidth GaN-on-Si laser diodes. Unlike conventional distributed Bragg feedback laser diodes with hundreds of gratings, we employed only a few precisely defined slot gratings to narrow the linewidth and mitigate the negative effects of grating fabrication on the device performance. The slot gratings were incorporated into the ridge of conventional Fabry-Pérot cavity laser diodes. A subsequent wet etching in a tetramethyl ammonium hydroxide solution not only effectively removed the damages induced by the dry etching, but also converted the rough and tilted slot sidewalls into smooth and vertical ones. As a result, the threshold current was reduced by over 20%, and the reverse leakage current was decreased by over three orders of magnitude. Therefore, the room-temperature electrically pumped narrow-linewidth GaN-on-Si laser diode has been successfully demonstrated.

Highlights

Direct-bandgap III-nitride semiconductors with a wide emission wavelength ranging from ultraviolet to infrared are the ideal materials for light-emitting diodes and laser diodes (LDs) [8,9,10]
We report room-temperature electrically pumped narrow-linewidth
The laser structure consisted of an n-type GaN contact layer, an n-type Al0.07 Ga0.93 N cladding layer (CL), three pairs of

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The sidewalls of the grating often suffer from roughness, poor steepness, and etching damage due to mask deformation, limitation of the aspect ratio, and high energy ion bombardment during the dry etching [27,28,29]. This would result in a large optical loss and low internal quantum. The threshold current of GaN-based narrow-linewidth LDs increased substantially, even by more than twice after the fabrication of Bragg gratings [30,31]. Substantial reductions in the threshold current and leakage current were clearly observed

Experimental Section

Results and Discussion

Conclusions