摘要:
研究了反向衬底偏压VB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IGMG特性,发现IGMG曲线的上升沿与下降沿随着|VB|的增大向右漂移.基于实验和理论模型分析,得出了VB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VB调节了表面电势φs在栅电压VG中的占有比重：|VB|增大时相同VG下φs会变小,φs的变化继而引发上升沿产生率因子gr减小以及下降沿产生率因子gf增大.进一步发现IGMG上升沿与下降沿的最大跨导GMR, GMF在对数坐标系下与VB成线性关系,并且随着|VB|增加而增大.由于漏电压VD在IGMG上升沿与下降沿中的作用不同,三种VD下GMR-VB曲线重合而GMF-VB曲线则产生差异.增大VD会增强gf随VG的变化,因此使得给定VB下的GMF变大.同时这却导致了更大VD下GMF-VB曲线变化的趋势减缓,随着VD从0.2 V变为0.6 V,曲线的斜率s从0.09减小到0.03.
Abstract:
The characteristics of gate-modulated generation (GMG) current IGMG in nano-scale LDD nMOSFET under the reverse substrate bias VB are investigated. It is found that the rising and falling edges of IGMG curve shift rightwards as|VB|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 VB modulates the proportion of surface potentialφs in the gate bias VG. φs decreases with|VB|increasing under a certain VG, and consequently the maximum generation factor of the rising edge (gr) diminishes and that of the falling edge (gf) augments. Further, it is found that the transconductance peaks of the rising edge (GMR) and falling edge (GMF) increase with|VB|increasing. Moreover, GMR and GMF both have the linear relationship with VB in log coordinate. Due to the different roles of drain bias VD on the rising and falling edge of IGMG curve, GMR keeps constant but GMF varies under different values of VD. Increasing VD can enhance the change of gf with VG, there by increasing GMF under a given VB. Also, this results in the fact that the trend of GMF increasing with|VB|increasing slows down under a larger VD: the slop of GMF-VB curve decreases from 0.09 to 0.03 as VD increases from 0.2 to 0.6 V.
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