Current–voltage (I–V) studies of Mo/γ-In₂Se₃/ZnO:Al diode structures

Mo/γ-In₂Se₃/ZnO : Al diode structures have been grown by vacuum deposition. In order to study the influence of the ZnO : Al electrode on the diode properties, ZnO : Al conductive and insulating films have been deposited by rf magnetron sputtering using a single Al₂O₃ doped ZnO target. These films have been characterized before their use in diodes. The electrical properties of ZnO : Al are controlled by the oxygen partial pressure during deposition. The effect of the composition on the I–V characteristics of γ-In₂Se₃ based diodes has been investigated. When γ-In₂Se₃ is doped with manganese there is no photovoltaic effect while there is when it is pure. It is shown that the I–V curves agree with Schottky theory only in the case of pure γ-In₂Se₃. When it is doped the I–V curves agree well with the trap-controlled space charge limited transport theory, which is attributed to the presence of a band of localized states present in the band gap of γ-In₂Se₃ after Mn doping.