Ge/Si Core/Shell Nanowire Structures for Tunneling Devices

Abstract

In this work, the concept of band-to-band tunneling (BTBT) devices is explored and the benefits of Ge/Si core/shell nanowire heterostructures (NWHs) as a material/geometry-related choice are discussed, namely increased performance accessible by 1D material systems that operate in the quantum capacitance limit (QCL), higher tunneling currents than available to Si-based tunneling structures, and compatibility of Ge/Si platforms with current manufacturing processes. The realization of such devices requires a degenerately doped source with an atomically abrupt source/channel interface. Toward this end, we present the electrical characterization of n+-Si shells around Ge cores that are close to the range suitable for the fabrication of optimized tunneling field effect transistors (TFETs). Specifically, we show that tuning the shell growth temperature from 470 to 600 °C has a significant impact on the morphology and transport properties of the grown Ge/Si core/shell nanowires.