New experimental findings on hot carrier transport under velocity saturation regime in Si MOSFETs

Abstract

The carrier transport properties under high field have been studied in Si MOSFETs experimentally from the following two points of view; velocity saturation and impact ionization. The electron and hole velocities in the inversion-layer were measured as a function of tangential electric field using high-resistive gate MOSFETs. It .has been found that the saturation velocity is dependent on the surface carrier concentration. The impact ionization rate was studied as a parameter of the length of the pinch-off region in MOSFETs. The suppression of the ionization rate and the enhancement of anisotropic impact ionization have been simultaneously observed at 81 K in the MOSFETs with the shorter length of pinch-off region. The non-stationary transport of hot carriers in the pinch-off region is responsible for these phenomena.

Comprehensive Study on Injection Velocity Enhancement in Dopant-Segregated Schottky MOSFETs

“…Actually, the R p for DSS is smaller than that for Conv, as shown in Fig.4. The contribution of R p to the drain current, I d , is distinguished from Quite good agreement of the present data with both Eq.1 and previous experimental work [6] was obtained. …”

Physical limitations and design for sub-0.1-?m MOS devices: Carrier velocity overshoot and performance fluctuation

“…2. Here, we consider only phonon scattering, so that m e µ E eff -1 / 3 [8]. As a result, the N a dependence of carrier velocity can be calculated using Eq.…”

“…In order to analyze v i degradation at high gate drives, we study the intrinsic velocity as a function of low field mobility, which depends on the effective transverse field E eff , based on an analysis of low field mobility characteristics [8]. Here, the gate drive dependence of E eff near the sub-100-nm region is assumed to be the same as in longchannel devices.…”

“…1(b) shows that the v e of bulk MOSFETs is smaller than the saturation velocity even at low gate drive. This velocity overshoot in SOI devices is considered an effect of nonstationary transport [5] caused by high mobility at low gate drive [8]. However, v e degrades with increasing gate drive, falling below v sat when the gate drive is greater than 0.8 V.…”

Device Physics and Electrical Performance of Bulk Silicon Mosfets

“…A decrease of about 2 decades is obtained in this case, demonstrating the impact of a cryogenic operation as regard to hot carrier energy. Indeed, these observations can be weH explained by the reduction with temperature and channel length of the pinch-off length in advanced devices [69,70], resulting from enhanced non-stationary transport phenomena. As shown in Fig.…”