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摘要: 半导体中的局域电子态和半导体的能带结构密切相关，揭示局域电子态和能带结构之间的内在关系是当前半导体电子理论的重要方面。而压力光谱实验对研究这种相互关系提供了重要手段。本文对GaP中深、浅两组能级的不同压力行为作了系统的实验研究。实验观察到无论在室温还是在低温，压力小于3.3 GPa时，以N陷阱束缚激子的发光过程为主，大于3.3 GPa时则以自由激子零声子过程为主，并且所有与N有关的陷阱态都具有压力的非线性行为。根据有效质量随压力的变化提出能谷中不同能量态具有不同的压力关系。基于有效质量随压力变化的能带格林函数方法，对N和NNi对的压力系数作了模型计算，其结果和陷阱态的压力行为符合得相当好。证实了带结构，尤其是能谷曲率随压力的变化是决定陷阱态压力行为的主要因素。Abstract: It has been well known that localized electronic states in semiconductors are closely related to the electronic band structure. In fact, exploration of the interrelation between localized electronic states and the band structure represents a basic aspect of the electronic theory of semiconductors. The photoluminescence under high pressure provide an important means for investigating this interrelation. The pressure behaviors of N and NNi traps as well as some other shallow states in GaP have been investigated. We find at both room temperature and 77 K, when the pressure is lower than 3.3 GPa, the single nitrogen traps dominate the luminescence while above 3.3 GPa the free exciton becomes important, we observe nonlinear behaviors associated with the binding of an exciton bound to N and NNi traps. This work shows that the pressure behaviors of whole series of exciton bund to N and NNi in GaP can be quantitatively explained on the basis of the band Green's function taking account of pressure-dependent effective masses. This further confirmed by a Green's function treatment based upon a proper pseudo band structure.
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Key words:
- GaP /
- N-Ni pair /
- iso-electronic traps /
- pressure behaviours /
- localized electronic states
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