Transport spectroscopy of low disorder silicon tunnel barriers with and without Sb implants

TL;DR

This study investigates silicon MOS split gate structures with and without Sb implants, analyzing transport properties and barrier characteristics to understand the effects of Sb donors on tunneling behavior at low temperatures.

Contribution

It provides a detailed analysis of tunnel barrier parameters and donor-related resonances, incorporating effects like FN tunneling and ICBL in a comprehensive model.

Findings

Barrier heights of 15-20 meV at resonances indicate shallow Sb donors.

Linear dependence of barrier parameters on gate voltage over wide ranges.

Deviations from standard models occur at large barriers.

Abstract

We present transport measurements of silicon MOS split gate structures with and without Sb implants. We observe classical point contact (PC) behavior that is free of any pronounced unintentional resonances at liquid He temperatures. The implanted device has resonances superposed on the point contact transport indicative of transport through the Sb donors. We fit the differential conductance to a rectangular tunnel barrier model with a linear barrier height dependence on source-drain voltage and non-linear dependence on gate bias. Effects such as Fowler-Nordheim (FN) tunneling and image charge barrier lowering (ICBL) are considered. Barrier heights and widths are estimated for the entire range of relevant biases. The barrier heights at the locations of some of the resonances for the implanted tunnel barrier are between 15-20 meV, which are consistent with transport through shallow partially hybridized Sb donors. The dependence of width and barrier height on gate voltage is found to be linear over a wide range of gate bias in the split gate geometry but deviates considerably when the barrier becomes large and is not described completely by standard 1D models such as FN or ICBL effects.