Proton irradiation induced defects in GaN: Rutherford backscattering and thermally stimulated current studies

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• 作者：T. Nakamura^a ; N. Nishikata^a ; K. Kamioka^a ; K. Kuriyama^a ; ^{kuri@ionbeam.hosei.ac.jp" class="auth_mail" title="E-mail the corresponding author} ; K. Kushida^b
• 关键词：GaN ; Proton irradiation ; Rutherford backscattering ; Thermally stimulated current ; Defects
• 刊名：Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
• 出版年：2016
• 出版时间：15 March 2016
• 年：2016
• 卷：371
• 期：Complete
• 页码：251-253
• 全文大小：627 K

文摘

The proton irradiation induced defects in GaN are studied by combining elastic recoil detection analysis (ERDA), thermally stimulated current (TSC), and Rutherford backscattering spectroscopy (RBS) measurements. The proton irradiation (peak concentration: 1.0 × 10¹⁵ cm⁻²) into GaN films with a thickness of 3 μm is performed using a 500 keV implanter. The proton concentration by a TRIM simulation is maximum at 3600 nm in depth, which means that the proton beam almost passes through the GaN film. The carrier concentration decreases three orders of magnitude to 10¹⁵ cm⁻³ by the proton irradiation, suggesting the existence of the proton irradiation-induced defects. The ERDA measurements using the 1.5 MeV helium beam can evaluate hydrogen from the surface to ∼300 nm. The hydrogen concentration at ∼220 nm is ∼8.3 × 10¹³ cm⁻² and ∼1.0 × 10¹⁴ cm⁻² for un-irradiated and as-irradiated samples, respectively, suggesting that electrical properties are almost not affected by hydrogen. TSC measurements show a broad spectrum at around 110 K which can be divided into three traps, P₁ (ionization energy 173 meV), P₂ (251 meV), and P₃ (330 meV). The peak intensity of P₁ is much larger than that of P₂ and P₃. These traps are related to the N vacancy and/or complex involving N vacancy (P₁), neutral Ga vacancy (V_Ga) (P₂), and complex involving V_Ga (P₃). The Ga displacement concentration evaluated by RBS measurements is 1.75 × 10¹⁹ cm⁻³ corresponding to 1/1000 of the Ga concentration in GaN. The observed Ga displacement may be origins of P₂ and P₃ traps.