Suppression of Effects of Backscattering from Drain Region on Double-Gate Metal–Oxide–Semiconductor Field-Effect Transistor Characteristics

Abstract

We have confirmed for the first time that backscattering from a drain region can markedly be suppressed by increasing the drain thickness of a decanano device. We have also investigated the effects of the backscattering phenomenon on the silicon decanano double-gate metal-oxide-semiconductor field-effect transistor (DG-MOSFET) characteristics. Ensemble Monte Carlo simulation is performed for our numerical experiment. Even if the rate of backscattering from the drain region decreases rapidly with increasing drain thickness, drain current increases only gradually. This gradual increase in drain current is due only to a rapid decrease in drain resistance. The backscattering phenomenon hardly affects DC characteristics, such as drain current. Moreover, when a small incremental change in backscattering rate decreases rapidly with increasing drain thickness, cutoff frequency increases markedly. This marked increase in cutoff frequency is due to both the rapid decrease in drain resistance and the rapid decrease in the small incremental change in backscattering rate. In paricular, the suppression of the backscattering phenomenon markedly improves AC characteristics, such as cutoff frequency. We believe that it becomes more important to analyze the backscattering phenomenon from the drain region along with miniaturization of such a decanano device.

Study of Backscattering Phenomenon from Drain Region of Silicon Decanano Diode Using Nonequilibrium Green's Function Approach

“…[6][7][8] However, we analyzed the backscattering effect from a drain region of the submicron/decanano devices on the carrier transport characteristics and device characteristics using Monte Carlo simulation. [9][10][11][12][13] It was already found in our previous research that the backscattering from the drain region markedly affects AC device characteristics. When a small incremental change in backscattered ratio, (BS ratio), is increased from 0.35 to 1.15%, the cutoff frequency ( f T ) of the device is degraded from 210 to 160 GHz.…”

“…where the external region is a region outside of the channel such as the source, drain, or electrode. Although this ''BS ratio'' is same as the ''BS rate'' defined in our previous paper, 12,13) we rename it here from ''BS rate'' to ''BS ratio'' to emphasize that it is the ratio of backscattered electrons, because ''BS rate'' causes misunderstanding of the frequency per unit time of backscattering. We analyzed the electron wave transport without scattering in the device using our developed NEGF simulator.…”

“…It is found from Fig. 7 that although the S ratio is almost the same, the BS ratio from the drain region increases with decreasing drain Since the BS ratio from the drain region is a reasonable indicator of AC performance such as cutoff frequency, 12) the BS ratio should be investigated in detail.…”

“…When a small incremental change in backscattered ratio, (BS ratio), is increased from 0.35 to 1.15%, the cutoff frequency ( f T ) of the device is degraded from 210 to 160 GHz. 12) It is desired that the quantum effect is completely incorporated for simulation of further smaller decanano devices. Recently, quantum mechanical device simulation using nonequilibrium Green's function (NEGF) method has been used for ultrasmall devices.…”

Analysis of Quantum Effects on Backscattering from Drain Region of Double-Gate Metal–Oxide–Semiconductor Field-Effect Transistor

“…8,13) We have investigated backscattering effect from the drain region of the future decanano DG-MOSFET from the point of view of electrical device characteristics, and a method of suppressing the backscattering was proposed in our previous work. 11) The backscattering phenomenon from the drain region can largely be suppressed by increasing the drain thickness. The backscattering negligibly affects DC characteristics such as drain current.…”