Structural evaluation of ions-implanted GaN films by photothermal deflection spectroscopy

Masatomo Sumiya,Hideo Iwai,Tohru Honda,Takeyoshi Onuma,Tomohiro Yamaguchi,Kiyotaka Fukuda

doi:10.1063/1.5052493

Abstract

We characterize the behavior caused by thermal annealing for C, O, Si and Mg ions implanted in GaN films by photothermal deflection spectroscopy (PDS) with respect to structural disorder and defect levels related to yellow luminescence. Although the implanted region damaged by ion bombardment is recovered by annealing, the FWHM values of ω(0002) evaluated by x-ray diffraction are almost independent of the temperature. However, the Urbach energy, as an index of structural disorder, evaluated by PDS is improved. Recovery of the structural disorder is likely to depend on the dose quantity rather than the acceleration voltage. Defect states in the band gap are reduced as well, though featured PDS signals related to the kind of implanted ion are hardly detected except for the carbon ion. The intensity of yellow luminescence at room temperature is enhanced according to the improvement of the Urbach energy and reduction of defect states in the band gap. PDS is useful for defect analysis of III-V nitride semiconductors that are electrically and optically inactive, such as ion-implantation samples, especially Mg-implanted GaN for achieving reliable p-type conduction.

Highlights

III-V nitride semiconductors, which enable solid-state lighting, have attracted the other applications of power electronics[1,2,3] owing to their high breakdown field and saturation velocity, and photovoltaic device owing to InxGa1-xN alloying, which enables coverage of the solar spectrum.[4,5]
Defect level and density can be conventionally characterized by deep level transient spectroscopy (DLTS).[6]
We prepare carbon, oxygen, silicon and magnesium ion-implanted standard samples for secondary ion mass spectroscopy (SIMS), with the expectation that identical defect levels can be detected for each sample by using photothermal deflection spectroscopy (PDS)

Summary

Introduction

III-V nitride semiconductors, which enable solid-state lighting, have attracted the other applications of power electronics[1,2,3] owing to their high breakdown field and saturation velocity, and photovoltaic device owing to InxGa1-xN alloying, which enables coverage of the solar spectrum.[4,5] Deep-level traps have an influence on the performance of these devices using high electric field and minority carriers. Masatomo Sumiya,1,a Kiyotaka Fukuda,[1,2] Hideo Iwai,[3] Tomohiro Yamaguchi,[2] Takeyoshi Onuma,[2] and Tohru Honda2 1Wide-Gap Semiconductor Group, National Institute for Materials Science, Namiki, Tsukuba 305-0044, Japan 2Department of Applied Physics, School of Advanced Engineering, Graduate School of Engineering, Kogakuin University, 2665-1 Nakano, Hachioji, Tokyo 192-0015, Japan 3Research Center for Advanced Measurement and Characterization, National Institute for Materials Science, Sengen, Tsukuba 305-0047, Japan (Received 18 August 2018; accepted 15 November 2018; published online 28 November 2018)

Results

Conclusion