N-polar InGaN-based LEDs fabricated on sapphire via pulsed sputtering

Kohei Ueno,Eiji Kishikawa,Hiroshi Fujioka,Jitsuo Ohta

doi:10.1063/1.4975617

Abstract

High-quality N-polar GaN epitaxial films with an atomically flat surface were grown on sapphire (0001) via pulsed sputtering deposition, and their structural and electrical properties were investigated. The crystalline quality of N-polar GaN improves with increasing film thickness and the full width at half maximum values of the x-ray rocking curves for 0002 and 101¯2 diffraction were 313 and 394 arcsec, respectively, at the film thickness of 6μm. Repeatable p-type doping in N-polar GaN films was achieved using Mg dopant, and their hole concentration and mobility can be controlled in the range of 8 × 1016–2 × 1018 cm−3 and 2–9 cm2V−1s−1, respectively. The activation energy of Mg in N-polar GaN based on a temperature-dependent Hall measurement was estimated to be 161 meV, which is comparable to that of the Ga-polar GaN. Based on these results, we demonstrated the fabrication of N-polar InGaN-based light emitting diodes with the long wavelength up to 609 nm.

Highlights

The growth of group-III nitrides on an N-polar plane has attracted much attention because they enable the growth of high-quality InGaN with high In composition owing to their thermal stability, which is higher than those grown on a Ga-polar plane.[1,2,3] In addition, in N-polar InGaN/GaN heterostructures, the spontaneous and piezoelectric polarization directions were reversed from those in
It is well known that molecular beam epitaxy (MBE) growth of nitride materials suffers from many problems such as a low growth rate and a low mass productivity
We have recently found that using a new growth technique called pulsed sputtering deposition (PSD) leads to the formation of device-quality nitride materials at a low cost and with a high growth rate.[11]

Summary

Introduction

The growth of group-III nitrides on an N-polar plane has attracted much attention because they enable the growth of high-quality InGaN with high In composition owing to their thermal stability, which is higher than those grown on a Ga-polar plane.[1,2,3] In addition, in N-polar InGaN/GaN heterostructures, the spontaneous and piezoelectric polarization directions were reversed from those in. N-polar InGaN-based LEDs fabricated on sapphire via pulsed sputtering

Results

Conclusion