Experimental Extraction of Ballisticity in Germanium Nanowire nMOSFETs

In this paper, we report the experimental extraction of ballistic transport parameters of highperformance Germanium Nanowire nMOSFETs (Ge NWTs) with lengths L
_NW
= 40-100 nm, width WNW = 40 nm, and height H
_NW
= 10 nm using temperature-dependent measurements. The extracted contact resistivity (ρc) and sheet resistance (Rsh) imply that parasitic series resistance (R
_SD
) of fabricated Ge NWTs is affected by Pc of the metalnGe (3.42× 10
^-5
Ω · cm
²
at 292 K), which decreases with the increase in temperature. Ballistic efficiency (BE) is found to be 22%-47% at 292 K depending on the dimension of the device. It decreases with increased temperature and increases with LNW scaling down to 40 nm. The transition region with fluctuating BE is observed near LNW = 50-60 nm, where the electron transport enters deeper into bthe allistic regime. BE is found to be sensitive to temperature and drops from 58% (170 K) to 37% (390 K) for LNW = 40-nm Ge NWT. Therefore, in order to maintain the high ballisticity of the devices, it is important to optimize the device structure and eliminate the self-heating effect.