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*2x10(--5)A /cm(2). 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/cm(2).