Determination of the concentration of impurities in GaN from photoluminescence and secondary-ion mass spectrometry

M. A. Reshchikov,H. Helava,A. Usikov,M. Vorobiov,O. Andrieiev,N. Izyumskaya,Yu. Makarov,V. Avrutin,K. Ding

doi:10.1038/s41598-020-59033-z

Abstract

Photoluminescence (PL) was used to estimate the concentration of carbon in GaN grown by hydride vapor phase epitaxy (HVPE). The PL data were compared with profiles of the impurities obtained from secondary ion mass spectrometry (SIMS) measurements. Comparison of PL and SIMS data has revealed that apparently high concentrations of C and O at depths up to 1 µm in SIMS profiles do not represent depth distributions of these species in the GaN matrix but are rather caused by post-growth surface contamination and knocking-in impurity species from the surface. In particular, PL analysis supplemented by reactive ion etching up to the depth of 400 nm indicates that the concentration of carbon in nitrogen sites is below 2–5 × 1015 cm−3 at any depth of GaN samples grown by HVPE. We demonstrate that PL is a very sensitive and reliable tool to determine the concentrations of impurities in the GaN matrix.

Highlights

Photoluminescence (PL) was used to estimate the concentration of carbon in GaN grown by hydride vapor phase epitaxy (HVPE)
One of them is the CN defect with the −/0 and 0/ + thermodynamic transition levels at 0.916 eV and ~0.3 eV, respectively, above the valence band[2,3,4,5]. This defect is responsible for the yellow luminescence (YL1) band with a maximum at 2.2 eV and zero phonon line (ZPL) at 2.59 eV in n-type GaN
Undoped or Si-doped GaN samples grown by hydride vapor phase epitaxy (HVPE) contain much less carbon (1015–1016 cm−3)[8,9,10,11], yet still the YL1 band may be strong in these samples due to high hole-capture cross-section for the CN defects[12]

Summary

Introduction

Photoluminescence (PL) was used to estimate the concentration of carbon in GaN grown by hydride vapor phase epitaxy (HVPE). Comparison of the PL data with SIMS depth profiles indicates that the concentration of the CN defect, which is responsible for YL1 band, is low and uniform for the studied GaN samples.

Results

Conclusion