Improved performance of GaN based light emitting diodes with ex-situ sputtered AlN nucleation layers

Shuo-Wei Chen,Heng Li,Tien-Chang Lu

doi:10.1063/1.4947299

Abstract

The crystal quality, electrical and optical properties of GaN based light emitting diodes (LEDs) with ex-situ sputtered physical vapor deposition (PVD) aluminum nitride (AlN) nucleation layers were investigated. It was found that the crystal quality in terms of defect density and x-ray diffraction linewidth was greatly improved in comparison to LEDs with in-situ low temperature GaN nucleation layer. The light output power was 3.7% increased and the reverse bias voltage of leakage current was twice on LEDs with ex-situ PVD AlN nucleation layers. However, larger compressive strain was discovered in LEDs with ex-situ PVD AlN nucleation layers. The study shows the potential and constrain in applying ex-situ PVD AlN nucleation layers to fabricate high quality GaN crystals in various optoelectronics.

Highlights

The crystal quality, electrical and optical properties of GaN based light emitting diodes (LEDs) with ex-situ sputtered physical vapor deposition (PVD) aluminum nitride (AlN) nucleation layers were investigated
It was found that the crystal quality in terms of defect density and x-ray diffraction linewidth was greatly improved in comparison to LEDs with in-situ low temperature GaN nucleation layer
For the purpose of decreasing the energy difference from lattice constant and thermal expansion coefficient mismatch between sapphire substrates and GaN, early pioneers applied in-situ low temperature AlN or GaN film to form the nucleation layer which provide a stable surface condition to grow the following bulk GaN.[7,8]

Summary

Introduction

The crystal quality, electrical and optical properties of GaN based light emitting diodes (LEDs) with ex-situ sputtered physical vapor deposition (PVD) aluminum nitride (AlN) nucleation layers were investigated. Improved performance of GaN based light emitting diodes with ex-situ sputtered AlN nucleation layers Shuo-Wei Chen,[1,2] Heng Li,[1] and Tien-Chang Lu1,a 1Department of Photonics, National Chiao Tung University, Hsinchu 300, Taiwan 2Epistar Corporation, Hsinchu 300, Taiwan (Received 7 February 2016; accepted 11 April 2016; published online 18 April 2016)

Results

Conclusion