Stoichiometric control of CuInSe 2 thin films using a molecular beam epitaxy technique

Abstract

The chalcopyrite phase of CuInSe materials has a phase stability region which extends several atomic percent from the stoichiometric composition. In this work, we apply thermal treatment to the film in the presence of a Se-beam flux immediately after film deposition. The duration for the treatment is long enough for chemical equilibrium to be reached. For In-rich films, an annealing at 400°C for 60 min is adequate. For Cu-rich films, caution should be taken to keep the compositions within the phase stability region in order to inhibit the formation of second phases. The Cu and In contents in the films did not significantly change after heat treatment. Photoluminescence (PL) measurements showed that a slightly In-rich film annealed in the Se-beam flux may reduce the PL transitions caused by antisite defects and greatly enhance the conduction band (CB) to V Cu transitions.