Energy Gaps and Stark Effect in Boron Nitride Nanoribbons

TL;DR

This study uses first-principles calculations to analyze the electronic properties and Stark effect in boron nitride nanoribbons with different edge shapes and widths, revealing how their band gaps respond to electric fields.

Contribution

It provides detailed insights into the size-dependent band gaps and electric field effects in armchair and zigzag boron nitride nanoribbons, highlighting edge state influences.

Findings

Armchair BNNRs show family-dependent oscillations in band gap with width.

Zigzag BNNRs have a monotonically decreasing band gap with width.

Electric fields modulate band gaps differently depending on edge type and field direction.

Abstract

A first-principles investigation of the electronic properties of boron nitride nanoribbons (BNNRs) having either armchair or zigzag shaped edges passivated by hydrogen with widths up to 10 nm is presented. Band gaps of armchair BNNRs exhibit family-dependent oscillations as the width increases and, for ribbons wider than 3 nm, converge to a constant value that is 0.02 eV smaller than the bulk band gap of a boron nitride sheet owing to the existence of very weak edge states. The band gap of zigzag BNNRs monotonically decreases and converges to a gap that is 0.7 eV smaller than the bulk gap due to the presence of strong edge states. When a transverse electric field is applied, the band gaps of armchair BNNRs decrease monotonically with the field strength. For the zigzag BNNRs, however, the band gaps and the carrier effective masses either increase or decrease depending on the direction and the strength of the field.