Probing of quantum energy levels in nanoscale body SOI-MOSFET: Experimental and simulation results

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.