Unraveling the structural and electronic properties of strained PbSe on GaAs

Abstract

Thin films of PbSe have been synthesized by molecular beam epitaxy on both GaAs(100) and GaAs(111)B substrates. Despite the smaller lattice constant of GaAs, the PbSe layers are (001)-oriented and undergo in-plane tensile strain on both substrates due to the thermal expansion coefficient mismatch between the materials. High resolution transmission electron microscopy observations reveal an abrupt and highly crystalline interface, not impacted by the tensile strain. The impact of strain on the electronic band structure is computed and found to induce an increase in the energy gap by as much as 10%.