Nitrogen-displacement-related electron traps in n-type GaN grown on a GaN freestanding substrate
Nitrogen-displacement-related electron traps in n-type GaN grown on a GaN freestanding substrate
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在 GaN 独立衬底上生长的 n 型 GaN 中与氮位移相关的电子陷阱
DOI：
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
J. Suda
中科院分区：
文献类型：
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作者：
M. Horita;T. Narita;T. Kachi;J. Suda
由本征点缺陷引起的能级由深能级瞬态谱（DLTS）确定。电子束（EB）照射在独立GaN衬底上通过金属有机气相外延生长的n型GaN层中产生氮空位（VN）和氮空位（NI），其中照射能量被选择为在100-401 keV内以仅置换GaN中的氮原子。在DLTS光谱中观察到两个电子陷阱，EE 1（0.13 eV）和EE 2（0.98 eV）。在401 keV的照射下，EE 1和EE 2的产生率分别为0.093和0.109 cm-1，这两个值几乎相等。在DLTS光谱记录的电子束照射的样品在能量范围从100至401 keV，EE 1和EE 2被发现同时出现在137 keV的照射能量，并观察到在能量大于137 keV。在与最近的第一性原理计算结果比较的基础上，我们将EE 1和EE 2峰分别归因于氮空位VN（+/0）和氮空位NI（0/−）。此外，退火导致这些陷阱的密度以相同的速度减少。EE 1和EE 2密度的降低可以通过NI的迁移以及随后与VN的复合来解释。从EE 1的辐照能量依赖性中获得GaN中氮的位移能为21.8 eV。
Energy levels due to intrinsic point defects are identified by deep-level transient spectroscopy (DLTS). Electron-beam (EB) irradiation created nitrogen vacancies (VN) and nitrogen interstitials (NI) in n-type GaN layers grown via metalorganic vapor phase epitaxy on freestanding GaN substrates, where the irradiation energies were selected to be within 100–401 keV to displace only nitrogen atoms in GaN. Two electron traps, EE1 (0.13 eV) and EE2 (0.98 eV), were observed in the DLTS spectra. The production rates of EE1 and EE2 were 0.093 and 0.109 cm−1 under 401 keV irradiation, which were nearly equal values. In the DLTS spectra recorded for EB-irradiated samples at the energy ranging from 100 to 401 keV, EE1 and EE2 were found to appear simultaneously at an irradiation energy of 137 keV and were observed at energies greater than 137 keV. On the basis of a comparison with the results of recent first-principles calculations, we attributed the EE1 and EE2 peaks to nitrogen vacancies VN (+/0) and nitrogen interstitials NI (0/−), respectively. Furthermore, annealing led to reductions of the densities of these traps at the same rate. The reduction of the densities of EE1 and EE2 can be explained by the migration of NI and the subsequent recombination with VN. The displacement energy of 21.8 eV for nitrogen in GaN was obtained from the irradiation-energy dependence of EE1.