硅中的过渡元素杂质能级

本文提出了半导体中过渡元素杂质的一个简单模型,用格林函数方法计算了硅中替代和间隙原子产生的杂质能级和波函数。发现两者的性质有很大的差别。替代原子只有当d原子能级V_d低于价带顶时才能产生杂质能级。它的波函数主要是悬键态,当能级靠近导带边时变成正键态。间隙原子只有当V_d高于价带顶时才能产生杂质能级。它的波函数主要是中心原子d态,当能级靠近导带边时变成弱反键态。最后定性地说明了过渡元素杂质能级的化学趋势和一些实验事实。 关键词：

DEEP LEVELS OF TRANSITION IMPURITIES IN SILICON

A simple model about transition impurities in semiconductors is proposed, and the impurity energy levels and wave functions produced by substitutional and interstitial atoms in silicon are calculated by Green's function method. It is shown that the properties of these two kinds of impurities are remarkably different. The substitutional atom can produce impurity energy level only when Vd, the atomic level of d state, is below the top of valence band. It's wave function is mainly dangling bond state, and gradually turns into bond state when the energy level approaehs the edge of conduction band. The interstitial atom can produce impurity energy level only when Vd is above the top of valence band. It's wave function is mainly d state of central atom and gradually turns into weak antibond state. Finally, the chemical trend and some experimental facts of transition impurity energy levels are qualitatively explained.