A Unified Theory and Fundamental Rules of Strain-dependent Doping Behaviors in Semiconductors

TL;DR

This paper introduces a unified theory explaining how strain affects defect energies and doping behaviors in semiconductors, providing fundamental rules to predict and enhance doping performance.

Contribution

The paper develops the first unified theoretical framework linking defect energy changes under strain to local volume variations, revealing fundamental rules for strain-dependent doping behaviors.

Findings

Defects exhibit parabolic or superlinear energy changes based on local volume change.

Three fundamental rules predict strain effects on defect formation, charge levels, and Fermi pinning.

The theory can improve doping strategies across various semiconductors.

Abstract

Enhancing the dopability of semiconductors via strain engineering is critical to improving their functionalities, which is, however, largely hindered by the lack of fundamental rules. In this Letter, for the first time, we develop a unified theory to understand the total energy changes of defects (or dopants) with different charge states under strains, which can exhibit either parabolic or superlinear behaviors, determined by the size of defect-induced local volume change ({\Delta}V). In general, {\Delta}V increases (decreases) when an electron is added (removed) to (from) the defect site. Consequently, in terms of this unified theory, three fundamental rules can be obtained to further understand or predict the diverse strain-dependent doping behaviors, i.e., defect formation energies, charge-state transition levels, and Fermi pinning levels, in semiconductors. These three fundamental rules could be generally applied to improve the doping performance or overcome the doping bottlenecks in various semiconductors.