Pulsed photo-ionization spectroscopy of traps in as-grown and neutron irradiated ammonothermally synthesized GaN

E Gaubas,J Mickevičius,J Pavlov,M Zajac,R Grigonis,V Rumbauskas,R Kucharski,T Čeponis,D Meškauskaite

doi:10.1038/s41598-018-38138-6

E Gaubas, J Mickevičius + Show 7 more

Open Access

https://doi.org/10.1038/s41598-018-38138-6

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Abstract

GaN-based structures are promising for production of radiation detectors and high-voltage high-frequency devices. Particle detectors made of GaN are beneficial as devices simultaneously generating of the optical and electrical signals. Photon-electron coupling cross-section is a parameter which relates radiation absorption and emission characteristics. On the other hand, photon-electron coupling cross-section together with photo-ionization energy are fingerprints of deep centres in material. In this work, the wafer fragments of the GaN grown by ammonothermal (AT) technology are studied to reveal the dominant defects introduced by growth procedures and reactor neutron irradiations in a wide range, 1012–1016 cm−2, of fluences. Several defects in the as-grown and irradiated material have been revealed by using the pulsed photo-ionization spectroscopy (PPIS) technique. The PPIS measurements were performed by combining femtosecond (40 fs) and nanosecond (4 ns) laser pulses emitted by optical parametric oscillators (OPO) to clarify the role of electron-phonon coupling. Variations of the operational characteristics of the tentative sensors, made of the AT GaN doped with Mg and Mn, under radiation damage by reactor neutrons have been considered.

Highlights

GaN is prospective to become the semiconductor generation for power electronics, for particle detectors and for other applications enabling much higher efficiency than silicon[1,2,3]
The impurity spectrum and dopant concentration values were estimated by secondary ion mass spectroscopy (SIMS)[11] and validated by electron spin resonance (ESR) measurements[7]
The relative concentrations Nd,L of different defects L can be evaluated by using a spectrum (e.g. UV-VIS range transmission) of an absorption coefficient α(hν), independently measured on the same sample, and its correlation with σ(hν) ~ UMW-PC,[0], as: Nd,L(hν) = α(hν)/σdL(hν)

Summary

Introduction

GaN is prospective to become the semiconductor generation for power electronics, for particle detectors and for other applications enabling much higher efficiency than silicon[1,2,3]. The photon-electron coupling cross-section and photo-ionization energy, ascribed to the definite defect, represent fingerprints of deep centres in material.

Results

Conclusion