First-principles Studies of Electron-Stimulated Si-H Bond Breaking

Hydrogen plays a crucial role in modern silicon devices by passivating silicon dangling bonds and eliminating electrically active mid-gap states. However, during device operation or exposure to radiation, hydrogen dissociation can occur, contributing significantly to degradation in silicon devices. Despite its importance, the exact mechanisms underlying this process remain poorly understood.

In this study, we investigate the precise mechanism underlying the dissociation of Si-H bonds. Employing first-principles calculations based on density functional theory (DFT), using the Maximally Localized Wannier function (MLWF) approach and the pseudo-atomic-orbital (PAO) method, we succesfully model the nuclear dynamics associated with the bonding and antibonding states of Si-H bonds.

Our findings indicate that electron-stimulated desorption can occur when high-energy electrons temporarily occupy the antibonding states of Si-H bonds, leading to dissociation events with quantified probability. This mechanism is supported by evidence from several experimental techniques, including scanning tunneling microscopy (STM) and low-energy electron collision studies.

This work is supported by AFOSR and by Samsung Semiconductor Inc.