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一、引言 对Ⅲ-Ⅴ族半导体混晶中普遍存在的施主中心(DX中心)的研究,近几年来很活跃。实验观察到AlGaAs中施主中心的主要性质:1.随Si、Sn和Te等施主杂质掺入,出现浅和深施主能级,其浓度N_S和N_D之比仅由混晶组分x决定,不随生长方法及生长条件变化,其浓度总和等于施主杂质浓度(见图1)。2.深能级的束缚能随组分,变化明显,x≈0.4束缚能最大。3.低温下对施主电子的光激发,产生持久光电导(PPC),且有很显著的组分依赖关
I. INTRODUCTION Research into donor centers (DX centers) that are prevalent in III-V semiconductor mixed crystals has been active in recent years. The main properties of donor centers in AlGaAs were observed experimentally.1. The shallow and deep donor levels appeared with the incorporation of donor impurities such as Si, Sn and Te. The concentrations of N_S and N_D were only determined by the mixed crystal component x, Growth methods and growth conditions change, the total concentration equal to the donor impurity concentration (see Figure 1). 2. The binding energy of deep level can vary obviously with components, and x≈0.4 has the largest binding energy. 3. Light excitation of donor electrons at low temperatures, resulting in long-lasting photoconductivity (PPC), with significant component dependence