Realizing the insulator-to-metal transition in Se-hyperdoped Si via non-equilibrium material processing

TL;DR

This study demonstrates an insulator-to-metal transition in selenium-hyperdoped silicon achieved through non-equilibrium processing, revealing increased conductivity and carrier concentration linked to the formation of an intermediate band.

Contribution

It introduces a method to induce the insulator-to-metal transition in Se-hyperdoped Si using ion implantation and flash lamp annealing, highlighting the role of an intermediate band.

Findings

Carrier concentration and conductivity increase with Se doping

Variable-range hopping with Coulomb gap observed below Mott limit

Insulator-to-metal transition linked to intermediate band formation

Abstract

We report on the insulator-to-metal transition in Se-hyperdoped Si layers driven by manipulating the Se concentration via non-equilibrium material processing, i.e. ion implantation followed by millisecond-flash lamp annealing. Electrical transport measurements reveal an increase of carrier concentration and conductivity with increasing Se concentration. For the semi-insulating sample with Se concentrations below the Mott limit, quantitative analysis of the temperature dependence of conductivity indicates a variable-range hopping mechanism with an exponent of s = 1/2 rather than 1/4, which implies a Coulomb gap at the Fermi level. The observed insulator-to-metal transition is attributed to the formation of an intermediate band in the Se-hyperdoped Si layers.