Si中S0/Se0,S0/Te0和Se0/Te0对的电子结构

利用紧束缚近似下的格林函数方法,讨论了Si中硫属元素混对杂质(即S⁰/Se⁰,S⁰/Te⁰和Se⁰/Te⁰)基态的电子结构。混对杂质在Si禁带中引入两个A₁能级,其中成键性的A₁能级位置在反键性的A₁能级之上。数值计算得到的混对杂质能级与实验符合得相当好。理论分析表明,在Si中测到的那些未定的比最近邻混对杂质能级更浅的能级(S⁰/Se⁰(X₁),S⁰/Te⁰(X₁),Se⁰/Te⁰(X₁)…)不是由非最近邻位型的混对杂质引入的。本文还指出了一个极性分子放入Si晶体中,两个不同原子间s波函数的转移方向与通常极性分子相反,并讨论其物理原因。 关键词：

ELECTRONIC STRUCTURES OF THE MIXED CHALCOGENIDE PAIRS IN Si

Using the Green's function method with a tight binding Hamiltonian, the electronic structures of the ground states of S⁰/Se⁰, S⁰/Te⁰ and Se⁰/Te⁰ mixed pairs in Si are investigated. Two A₁ symmetrical states are introduced by the mixed pairs, the bonding A₁ state is higher than the antibonding A₁ state. The numerical results of the energy leveals of mixed pairs are obtained, which are in agreement with the experimental observations. It looks likely that the unidentified shallower energy leveals (S⁰/Se⁰ (X₁), S⁰/Te⁰ (X₁), Se⁰/Te⁰ (X₁)…) are not introduced by the mixed pairs with other non-nearest positions. We note that the transfer direction of the s wavefuction between two different defect atoms in Si is reversed as compare with the ordinary diatomic molecule case. The physical reason is discussed.