深能级陷阱对FET的光瞬态特性、等效噪声电流和漏电流升高的影响

本文基于位于准费密能级下深受主陷阱和剩余空穴,在平衡(无光照)和非平衡(有光照)条件下单位时间内空穴浓度变化率的微分方程基础上,导出了指数衰减理论方程,可很好地解释深能级对FET光脉冲瞬态特性的影响,指出了深能级是衰减长尾产生的根本原因,并测定了GaAs MESFET、GaAlAs TEGFET Si JFET的光脉冲瞬态特性,验证了理论模型的准确性。探讨了能级深度E_T等因素对衰减曲线的影响。测定了上述三类器件的等效噪声电压与频率f之间的关系,应用文献[6]的公式得出了相应的等效噪声关键词：

THE EFFECT OF DEEP LEVEL TRAP ON PHOTO-TRANSIENT CHARACTERISTICS, EQUIVALENT NOISE CURRENT AND INCREMENT OF DRAIN CURRENT FOR FET

In this paper, based on the differential equations of Change rate of hole concentration for deep acceptor trap and excess hole located below quasi-Fermi level under equilibrium or non-equilibrium state (with light illumination), an exponential attenuation equation has been deduced. It is capable of explaining the effect of deep level trap on photo-pulse transient characteristics, satisfactorily. We indicate chat the deep trap is the primary cause of producing the long tail of attenuation curve. The photo-pulse transient characteristic curves of GaAs MESFET, GaAl-As TEGFET and Si JFET were measured. The experimental results could check the exactness of the theory. The effect of deep level depth E_T, concentration N_T and so on attenuation curves has also been discussed. The dependence of equivalent noise voltage E_eq on frequence for the above three devices were measured. The relations between equivalent noise current I_eq and f, and between I_eq and effect deep level concentration N_T,eff were obtained using the equations in ref. (6). In this way, the effect of deep level trap on noise may be obtained. The relation between △N_T,eff and drift of drain current △I_D could be calculated. They were in well agreement with the experimental results. Hence, the increase of △I_D also results from the deep level trap.