First-principles calculations of thermal electron emission from H$^-$ in silicon

TL;DR

This study uses first-principles calculations to analyze the thermal electron emission process of hydrogen negative ions in silicon, revealing a two-step mechanism consistent with experimental data.

Contribution

It provides a detailed first-principles model of H$^-$ thermal emission in silicon, clarifying the process and identifying the rate-limiting step, which was not previously well understood.

Findings

H$^-$ diffusion from tetrahedral to bond-center site is rate-limiting

Nonradiative transition occurs rapidly at the body-center site

Calculated emission rate matches experimental deep level transient spectroscopy data

Abstract

Thermal electron emission process of a hydrogen impurity is an important topic of fundamental semiconductor physics. Despite of decades-long study, theory is not established yet. Here, we study the process of $\mathrm{H}^{-}$ in silicon, $\mathrm{H^{-}} \to \mathrm{H^{0}} + e^{-}$, using a first-principles calculation. Our calculation indicates that the process consists of two steps: slow diffusion of H$^{-}$ from a tetrahedral site to a bond-center site, which is the rate-limiting step, and faster nonradiative transition from $\mathrm{H}^{-}$ to $\mathrm{H}^{0} + e^{-}$ that occurs subsequently at the body-center site. The calculated rate is consistent with a deep level transient spectroscopy experiment