The effects of applied and internal strain on the electronic propertiesof amorphous silicon

Abstract

Abstract The elasto conductivity has been investigated in a series of doped and undoped glow discharge (g.d.) a-Si specimens under applied tensile and compressive linear strains, S. A periodic bending-couple was applied to the glass substrate and conductance changes were recorded by phase-sensitive detection. The elastoconductivity parameter K= — (1/S)(δ[Sgrave]/[Sgrave]) was studied as a function of Fermi-level position, temperature, specimen thickness and angle between current and strain. The experiments were also extended to specimens in which phonon-assisted hopping predominated. It was found that irrespective of the transport mechanism, the strain causes a small unidirectional shift δef (∼ meV) of the Fermi energy. δefdepends critically on the position of efwithin the mobility gap. A plot of the dependence of K on ec-ef shows peaks at 0–6eV and about 1.0eV which are related to the dependence of the pre-factor [sgrave]o on ec-ef. It is concluded that the δef produced by the strain is linked to the mov...