Fabrication of SnS2/SnS heterojunction thin film diodes by plasma-enhanced chemical vapor deposition

Heterojunction based on Sn–S compounds, SnS and SnS2, have been prepared by plasma-enhanced chemical vapor deposition (PECVD). The semiconductor materials SnS and SnS2 were obtained by the decomposition of the gas precursors SnCl4 and H2S in a capacitive-coupled RF plasma-deposition chamber. Corning glass with a transparent conductor oxide (TCO) thin film was used as substrate. The structure of the diode was glass/TCO/n-type SnS2/p-type SnS/Al. The contact between the n-type and p-type Sn–S compounds was found to be rectifying. The estimate reverse saturation density current was 1.2×10−5 A/cm2. The ratio of forward-to-reverse current exceeded 300 within the range of applied voltages of −1.0 to 1.0 V and the estimated diode factor was 2.7. A photovoltaic effect was observed under illumination giving an open circuit voltage of 0.35 V and a small short circuit current density with a value of 1.5 mA/cm2.