Anomalous relaxations and chemical trends at III-V nitride non-polar surfaces

TL;DR

This paper investigates the unique surface relaxations of nonpolar III-V nitride surfaces, revealing anomalous behaviors linked to ionicity and bonding strength, supported by first-principles calculations and comparisons with related compounds.

Contribution

It provides a detailed first-principles analysis of surface relaxations in III-V nitrides, highlighting anomalous behaviors and their relation to ionicity and bonding, which was not previously characterized.

Findings

Nitrides exhibit anomalous surface relaxation behaviors.

Ionities and bonding strengths influence surface relaxation patterns.

Analogies between nitrides and Zn II-VI compounds are established.

Abstract

Relaxations at nonpolar surfaces of III-V compounds result from a competition between dehybridization and charge transfer. First principles calculations for the (110) and (10$\bar{1}$0) faces of zincblende and wurtzite AlN, GaN and InN reveal an anomalous behavior as compared with ordinary III-V semiconductors. Additional calculations for GaAs and ZnO suggest close analogies with the latter. We interpret our results in terms of the larger ionicity (charge asymmetry) and bonding strength (cohesive energy) in the nitrides with respect to other III-V compounds, both essentially due to the strong valence potential and absence of $p$ core states in the lighter anion. The same interpretation applies to Zn II-VI compounds.