Characterisation of defects in p-GaN by admittance spectroscopy

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• 作者：O.S. Elsherif^a ; ^{osama.s.el-sherif@student.shu.ac.uk} ; ^{Elsherif.o@gmail.com} ; K.D. Vernon-Parry^a ; J.H. Evans-Freeman^b ; R.J. Airey^c ; M. Kappers^d ; C.J. Humphreys^d
• 关键词：GaN ; Threading dislocations ; Mg doping ; Defects ; Admittance spectroscopy
• 刊名：Physica B
• 出版年：2012
• 期刊代码：53_09214526
• 类别：ph
• 出版时间：1 August, 2012
• 卷：407
• 期：15
• 页码：2960-2963
• 文件大小：344 K

摘要

Mg-doped GaN films have been grown on (0 0 0 1) sapphire using metal organic vapour phase epitaxy. Use of different buffer layer strategies caused the threading dislocation density (TDD) in the GaN to be either approximately 2脳10⁹  cm^鈭? or 1脳10¹⁰ cm^鈭?. Frequency-dependent capacitance and conductance measurements at temperatures up to 450 K have been used to study the electronic states associated with the Mg doping, and to determine how these are affected by the TDD. Admittance spectroscopy of the films finds a single impurity-related acceptor level with an activation energy of 160卤10 meV for [Mg] of about 1脳10¹⁹ cm^鈭?, and 120卤10 eV as the Mg precursor flux decreased. This level is thought to be associated with the Mg acceptor state. The TDD has no discernible effect on the trap detected by admittance spectroscopy. We compare these results with cathodoluminescence measurements reported in the literature, which reveal that most threading dislocations are non-radiative recombination centres, and discuss possible reasons why our admittance spectroscopy have not detected electrically active defects associated with threading dislocations.