Monotonic variation in carbon-related defects with Fermi level in different conductive types of GaN

Yuheng Zhang,Jing Yang,Zongshun Liu,Feng Liang,Degang Zhao,Ping Chen

doi:10.1063/5.0054483

Abstract

This study examined the photoluminescence (PL) of samples of GaN and found that the intensity of the peak of luminescence related to carbon impurities in p-GaN changed with the doping concentration of Mg. However, the results of a secondary ion mass spectrometry test showed that the concentration of carbon impurities did not change correspondingly. Moreover, we observed changes in the relative strength of the peak related to carbon impurities in the PL spectra of a series of samples of n-type conductive GaN. This suggests a connection between the behavior of carbon-related defects and the conductivity of GaN. The results show that the variation in carbon-related defects was monotonic. As the Fermi level approached the conductive band, carbon-related defects that generated higher-energy photonics became more dominant in the PL spectra in the series from p-type to n-type GaN.

Highlights

GaN-based compounds and their alloys are the third generation of semiconductor materials with a wide energy bandgap. They are considered important owing to their wide-ranging prospects for commercial applications, including in light-emitting diodes (LEDs),1 laser diodes (LDs),2 high-electron-mobility transistors (HEMTs),3 and Si substrate-based devices
As shown in the figure, there were three groups of distinct luminescence peaks: the sharp near-band edge emission (NBE) at 3.4 eV, which was induced by the intrinsic transition of GaN, the violet luminescence (VL) band at 3.2 eV, and the yellow luminescence (YL) band with a broad spectral range that peaked at 2.3 eV
The CN–ON complex is expected to produce a PL band with a maximum at 2.25 eV and a zero-phonon line (ZPL) at 2.73 eV,7,15 which indicates that CN and the CN–ON complex may be the reasonable origin of the YL band in this study

Summary

Introduction

GaN-based compounds and their alloys are the third generation of semiconductor materials with a wide energy bandgap. They are considered important owing to their wide-ranging prospects for commercial applications, including in light-emitting diodes (LEDs), laser diodes (LDs), high-electron-mobility transistors (HEMTs), and Si substrate-based devices.. The results of experiments have shown that carbon impurities may act as a donor to compensate for magnesium in p-type GaN and increase its resistivity.. Carbon can act as an acceptor and increase the resistivity of n-type GaN.. The semi-insulating behavior of undoped GaN may result from the self-compensation effect, i.e., owing to the simultaneous incorporation of CN acceptors and CGa donors in nearly equal concentrations.. The point defects induced by carbon impurities can take different forms in GaN, such as substitutional defects (CN, CGa), interstitial defect (Ci), and complexes. First-principles calculations based on density theory have consistently shown that carbon can act as an acceptor when substituted into the site of N or as a donor when it occupies the position of Ga. The results of experiments have shown that carbon impurities may act as a donor to compensate for magnesium in p-type GaN and increase its resistivity. carbon can act as an acceptor and increase the resistivity of n-type GaN. In addition, the semi-insulating behavior of undoped GaN may result from the self-compensation effect, i.e., owing to the simultaneous incorporation of CN acceptors and CGa donors in nearly equal concentrations. the role that carbon impurities may play in GaN is not fixed

Methods

Results

Conclusion