C_(70)/GaAs异质结的电学性质

Electrical Properties of Solid C _(70)/GaAs Heterojunctions

在高真空系统中 ,将 C70 膜淀积在 n-和 p- Ga As(10 0 )衬底上 ,制成 C70 / n- Ga As和 C70 / p- Ga As两种接触 ,并对它们的电学性质作了研究 .结果发现两种接触均为强整流结 ,在偏压为± 1V时 ,C70 / n- Ga As和 C70 / p- Ga As接触的整流比分别大于 10 6 和 10 4,并且它们的理想因子都接近于 1.当正向偏压固定时 ,它们的电流均是温度倒数的指数函数 ,从中确定两种异质结的有效势垒高度分别为 0 .784和 0 .5 31e V .用深能级瞬态谱 (DL TS)在 C70 / Ga As界面上观察到电子陷阱 E(0 .6 40 e V )和空穴陷阱 H3(0 .82 2 e V) ,以及用电容 -时间 (C- t)技术在固体 C70 中观测到两种空穴陷阱 H4(1.15 5 e V)和 H5 (0 .85 6 e V) .E(0 .6 40 e V)和 H3(0 .82 2 e V)的密度均小于 10 1 2 / cm2 ,可以得出结论 :固体 C70 对 Ga

Solid C 70 /GaAs contacts are fabricated by vacuum d ep osition of solid C 70 films on the n-and p-type epitaxial GaAs (100) subs trates and their electrical properties are studied.It is found that these two ki nds of contacts are both strongly rectifying heterojunctions.The rectification r atios are higher than 10 6 and 10 4 respectively,for the solid C 70 /n-Ga As and C 70 /p-GaAs contacts at the bias of ±1V.At a fixed forward voltage ,the current is an exponential function of the reciprocal temperature,from which ,the effective barrier heights can be determined to be 0 784 and 0 531eV for C 70 /n-GaAs and C 70 /p-GaAs contacts,respectively.A electron trap, E (0 640eV),and a hole trap, H 3(0 822eV) are observed at the solid C 70 /GaAs interfaces with deep level capacitance transient spectroscopy (DLT S).Two hole traps in solid C 70 are investigated by means of capacita nce-time ( C-t ) technique for the first time.It shows that the GaAs surface s can be passivated by the C 70 films very well.