The metal-insulator transition and lattice distortion in semiconductors

TL;DR

This paper explores the relationship between metal-insulator transitions and lattice distortions in semiconductors, analyzing how atomic relaxation and phase transitions influence bandgap properties and structural symmetry.

Contribution

It introduces a relation between excitation energy and bandgap width, and examines how phase transitions induce specific lattice distortions in various semiconductor structures.

Findings

Metal-insulator transition causes weak lattice distortions in semiconductors.

Atomic relaxation affects temperature and pressure dependence of bandgap.

Bandgap changes are linked to ferroelectric and antiferroelectric transitions.

Abstract

A relation between the energy of an elementary `insulating' excitation corresponding to the metal-insulator transition and the bandgap width in a semiconductor is obtained. An effect of atomic relaxation on the temperature and pressure dependence of the bandgap width is considered. It is shown that the metal-insulator transition in a semiconductor causes a weak rhombohedral or monoclinic distortion in the case of a diamond and zincblende structure and a weak tetragonal or orthorhombic distortion in the case of a rocksalt structure. A change in the bandgap associated with a ferroelectric (antiferroelectric) transition in a semiconductor is also obtained.