M-I-S-S structure based silicon and TCO

Wide attention has been given to the heterojunction Semiconductor-Insulator-Semiconductor S-I-S solar cells which present the same performances as the Metal-Insulator- Semiconductor M-I-S heteroj unctions. In the former, the top semiconductor is a transparent degenerated semiconductor thin film. Among the various transparent conducting oxides, TCOs, tin oxide and zinc oxide have received a big attention because of their abundance in nature as well as their electrical, optical, and chemical properties. The use of zinc oxide on one side of silicon and tin oxide on the other side gives us a new heterojunction configuration Metal- Insulator-Semiconductor-Semiconductor (M-I-S-S). This paper reports on the study of the possible M-I-S-S configuration ZnO/SiO₂/Si/SnO₂, and its photovoltaic application. To insure this application a compromise between the silicon carrier concentration and that of tin oxide is respected in such a way SnO₂/Si constitutes an ohmic contact whereas ZnO/SiO₂/Si constitutes a Schottky diode. The choice of the three materials emplacement is conditioned by the work function of both tin oxide SnO₂, zinc oxide ZnO, and n and p type silicon.