Effect of Cu on InSe/Si(111) heterojunctions

Abstract

The effect of sequential deposition of Cu onto a 300 A-thick film of layered InSe epitaxially grown onto a Si(111) substrate, has been studied by Auger electron spectroscopy (AES), low energy electron diffraction (LEED) and photoemission yield spectroscopy (PYS). Cu coverages were from a few hundredth of a monolayer (in terms of InSe atomic surface plane: 1 ML = 7.2 × 10 14 at/cm 2 , that is 0.85 A of Cu-metal) to 300 ML. The effect of annealings up to 370 °C was also studied. It is shown that Cu has first a non uniform bulk interaction with InSe which looks like an insertion which saturates at 1 ML of Cu per In 2 Se 2 single layer. Then it forms islands which fully mask the surface beyond about 150 ML coverage (130 A of Cu-metal). Upon annealings beyond 300 °C, the Si substrate behaves as a Cu sink.