Abstract
In the efforts to address the need for developing ultra-fast computers based on combined electronic and optical signal processing using silicon-based nanoscale devices, new types of transistors have been developed. Ultra-Thin Body and Nano-Scale Body (NSB) Silicon-On-Insulator Metal–Oxide-Semiconductor Field-Effect-Transistor devices, sharing a similar W/L but with a channel thickness of, respectively, 46 nm and down to 1.6 nm, have been fabricated using a selective Gate-Recessed Channel process on the same silicon wafer, and electrically tested at room (300 K) and low (77 K and 4.7 K) temperatures. In addition to the observed drain current values, which were found to be different by three orders of magnitude, quantum steps have been identified in the NSB transfer curves when measured at low temperatures. Since the NSB device's channel is part of a quantum well structure, the steps can point to discrete levels of energy. Such an approach can lead the way to some opportunities toward inter-subband emitting devices. Location of discrete steps is evidence of indirect-to-direct transition in ultra-thin silicon.
Highlights
There is a clear advantage to using Nano-Scale Body (NSB) transistors since their quantum well structure enables the discretization of the energy levels, leading to a step-like phenomenon in the transfer characteristics and possibly to radiative recombination in Inter Sub-Band Transition (ISBT)
Ultra-Thin Body (UTB) and NSB devices have been simultaneously fabricated on the same SOI wafer, using a selective “Gate Recessed” (GRC) process
As part of the investigations, it was necessary to verify the electrical functionality of the UTB (46 nm channel thickness) and NSB (2.4 nm thickness) transistors using standard output characteristics curves, i.e., drain current IDS vs. drain voltage VDS, as shown below in Figs. 2 and 3, respectively, 0021-8979/2018/124(12)/124306/16
Summary
For Silicon-On-Insulator Metal–Oxide-Semiconductor Field-Effect-Transistors (SOI-MOSFETs), the critical scaling of the channel thickness from deca-nanometer, for so-called Ultra-Thin Body (UTB) devices, to the nanometer node in so-called Nano-Scale Body (NSB) and non-planar Fin-FETs is still a bottleneck of the current VLSI technology. A major disadvantage of such SOI NSB and Fin-FETs is a severe increase of parasitic source and drain resistances as silicon film thicknesses drop below the 10 nm limit. In this perspective, several comparative studies of the electrical characteristics between UTB and NSB at room and low temperatures, as well as anomalous transport behavior, have recently been presented. On the other hand, there is a clear advantage to using NSB transistors since their quantum well structure enables the discretization of the energy levels, leading to a step-like phenomenon in the transfer characteristics and possibly to radiative recombination in Inter Sub-Band Transition (ISBT). A major disadvantage of such SOI NSB and Fin-FETs is a severe increase of parasitic source and drain resistances as silicon film thicknesses drop below the 10 nm limit.. A major disadvantage of such SOI NSB and Fin-FETs is a severe increase of parasitic source and drain resistances as silicon film thicknesses drop below the 10 nm limit.2 In this perspective, several comparative studies of the electrical characteristics between UTB and NSB at room and low temperatures, as well as anomalous transport behavior, have recently been presented.. Measurements of the transfer characteristics of UTB device with those of NSB SOI-MOSFET devices, having respective channel thicknesses of 46 nm, 2.4 nm, and 1.6 nm, are presented and discussed. An analytic model, based on quantum mechanics and statistical physics, is developed to explain these important experimental results
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