反向衬底偏压下纳米N沟道金属氧化物半导体场效应晶体管中栅调制界面产生电流特性研究

研究了反向衬底偏压V_B下纳米N沟道金属氧化物半导体场效应晶体管中栅调制界面产生(GMG)电流I_GMG特性, 发现I_GMG曲线的上升沿与下降沿随着|V_B|的增大向右漂移. 基于实验和理论模型分析, 得出了V_B与这种漂移之间的物理作用机制, 漂移现象的产生归因于衬底偏压V_B 调节了表面电势φ_s在栅电压V_G 中的占有比重: |V_B|增大时相同V_G下φ_s会变小, φ_s 的变化继而引发上升沿产生率因子g_r减小以及下降沿产生率因子g_f增大. 进一步发现I_GMG 上升沿与下降沿的最大跨导G_MR, G_MF 在对数坐标系下与V_B成线性关系, 并且随着|V_B|增加而增大. 由于漏电压V_D在I_GMG 上升沿与下降沿中的作用不同, 三种V_D下G_MR-V_B曲线重合而G_MF-V_B曲线则产生差异. 增大V_D 会增强g_f 随V_G的变化, 因此使得给定V_B 下的G_MF变大. 同时这却导致了更大V_D下G_MF-V_B 曲线变化的趋势减缓, 随着V_D从0.2 V变为0.6 V, 曲线的斜率s从0.09减小到0.03. 关键词： 产生电流 表面势 衬底偏压 N沟道金属氧化物半导体场效应晶体管

Characteristics of gate-modulated generation current under the reverse substrate bias in nano-nMOSFET

The characteristics of gate-modulated generation (GMG) current I_GMG in nano-scale LDD nMOSFET under the reverse substrate bias V_B are investigated. It is found that the rising and falling edges of I_GMG curve shift rightwards as |V_B| increases. On the basis of experimental and theoretical analysis, the physical mechanism behind this shift phenomenon is attained. The shift phenomenon is ascribed from the fact that V_B modulates the proportion of surface potential φ_s in the gate bias V_G. φ_s decreases with |V_B| increasing under a certain V_G, and consequently the maximum generation factor of the rising edge (g_r) diminishes and that of the falling edge (g_f) augments. Further, it is found that the transconductance peaks of the rising edge (G_MR) and falling edge (G_MF) increase with |V_B| increasing. Moreover, G_MR and G_MF both have the linear relationship with V_B in log coordinate. Due to the different roles of drain bias V_D on the rising and falling edge of I_GMG curve, G_MR keeps constant but G_MF varies under different values of V_D. Increasing V_D can enhance the change of g_f with V_G, there by increasing G_MF under a given V_B. Also, this results in the fact that the trend of G_MF increasing with |V_B| increasing slows down under a larger V_D: the slop of G_MF-V_B curve decreases from 0.09 to 0.03 as V_D increases from 0.2 to 0.6 V.
Keywords： generation current surface potential substrate bias nMOSFET