Fabrication of n-ZnS/p-SnS, n-ZnO/p-SnS, and n-SnO2/p-SnS heterojunctions by 2-step SILAR process for photodetector applications

In this work, we present the fabrication and detailed analysis of three functional heterojunctions based on SnS. Unlike most of the previous reports, all semiconductor layers in the heterojunctions were deposited using the low-cost SILAR technique. The ZnS, ZnO, and SnO2 films, each with a thickness of 400 nm, were grown on a previously deposited 800 nm SnS layer, forming n-ZnS/p-SnS, n-ZnO/p-SnS, and n-SnO2/p-SnS heterojunctions. Current-voltage characteristics confirmed the successful formation of p-n junctions. Various models were used to estimate junction parameters such as diode ideality factor, barrier height, and series resistance. The fabricated diodes exhibited a prominent photo response under illumination. Photodetection figures of merit were estimated for all the devices. n-ZnS/p-SnS showed 0.003 mu A response current, with 0.27 sensitivity. The responsivity observed was around 0.6 mu A /W with LDR of 2.09 dB. The specific detectivity was 10(6) Jones. Similarly, n-ZnO/pSnS showed 0.021 mu A response current, with 0.38 sensitivity. The responsivity observed was around 4.2 mu A /W with LDR of 2.80 dB. The specific detectivity was 10(6) Jones. However, n-SnO2/p-SnS showed remarkable figures of merit such as 2.4 mu A response current, with 8.40 sensitivity. The responsivity observed was around 488 mu A/W with LDR of 19.47 dB. The specific detectivity was 10(9) Jones. The rise and decay time of the photocurrent were 5 and 7 s, respectively.