Transition-metal ions in β-Ga2O3 crystals: Identification of Ni acceptors
Transition-metal ions in β-Ga2O3 crystals: Identification of Ni acceptors
复制标题
β-Ga2O3 晶体中的过渡金属离子：Ni 受体的识别
DOI：
10.1063/5.0126467
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发表时间：
2022
影响因子：
3.2
通讯作者：
L. Halliburton
中科院分区：
文献类型：
--
作者：
T. Gustafson;N. Giles;B. Holloway;J. Jesenovec;B. Dutton;J. McCloy;M. McCluskey;L. Halliburton
β-Ga 2 O3晶体中的过渡金属离子（Ni、Cu和Zn）在带隙的下半部分形成深受主能级。在本研究中，我们表征了直拉法生长的晶体中的Ni受体，发现它们的（0/−）能级比价带最大值高出约1.40 eV。Ni 2+（3d 8）和Ni 3+（3d 7）受体都存在于生长的晶体中。还存在非故意的Ir 3+（5d 6）和Ir 4+（5d 5）供体。中性Ni 3+受体具有低自旋S = 1/2基态，并且容易用电子顺磁共振（EPR）监测。这些受体的g矩阵的主值为2.131、2.138和2.233。在X波段（9.4GHz），EPR没有观察到Ni ~（2+）的单电离态，但具有顺磁性。Ir 4+供体用EPR和红外吸收光谱法监测。在室温下将Ni掺杂的β-Ga 2 O3晶体暴露于275 nm的光下，随着电子从受主向施主移动，Ni 3+离子的浓度增加，而Ir 4+离子的浓度降低。在照射之后，将晶体加热到375 °C以上恢复Ni 3+和Ir 4+离子的初始浓度。在303和442 nm附近的宽的光学吸收带的峰值归因于Ni 3+受体。
Transition-metal ions (Ni, Cu, and Zn) in β-Ga2O3 crystals form deep acceptor levels in the lower half of the bandgap. In the present study, we characterize the Ni acceptors in a Czochralski-grown crystal and find that their (0/−) level is approximately 1.40 eV above the maximum of the valence band. Both Ni2+ (3d8) and Ni3+ (3d7) acceptors are present in the as-grown crystal. Also present are unintentional Ir3+ (5d6) and Ir4+ (5d5) donors. The neutral Ni3+ acceptors have a low-spin S = 1/2 ground state and are easily monitored with electron paramagnetic resonance (EPR). Principal values of the g matrix for these acceptors are 2.131, 2.138, and 2.233. Although paramagnetic, the singly ionized Ni2+ acceptors are not seen with EPR at X band (9.4 GHz). The Ir4+ donors are monitored with EPR and with infrared absorption spectroscopy. Exposing the Ni-doped β-Ga2O3 crystal to 275 nm light at room temperature increases the concentration of Ni3+ ions and reduces the concentration of Ir4+ ions as electrons move from the acceptors to the donors. After illumination, heating the crystal above 375 °C restores the initial concentrations of the Ni3+ and Ir4+ ions. Broad optical absorption bands peaking near 303 and 442 nm are attributed to the Ni3+ acceptors.