Experimental Investigation of Si/SnOx Heterojunction for Its Tunable Optoelectronic Properties

We report growth and characterization of n-Si/p-SnOx heterojunction using RF sputtering for deposition of p-type SnOx under controlled growth oxygen pressure over n-type silicon (Si) wafer. The heterojunction properties of Si/SnOx were varied by controlling the growth oxygen pressure of SnOx. Several characterization techniques, including PL (photoluminescence), AFM (atomic force microscopy), FESEM (field emission scanning electron microscopy), XRD, I-V characteristics and Hall measurement, were conducted to analyze the structural, optical, and electrical properties of the n-Si/p-SnOx heterojunction. The knee voltage (Vknee), or cut-in voltage, was calculated by analyzing the gradient of the dark current-voltage (J-V) curves when the bias was applied in the forward direction. The Vknee values for type-I, type-II, and type-III n-Si/p-SnOx heterojunctions were determined to be 0.62 V, 0.84 V, and 1.0 V, respectively. The ideality factors (n1 and n2) were determined to be 1.52, 2.22, 3.52, and 8.41, 9.31, 10.34, respectively, for various heterojunction types. The reverse saturation current densities, J01 and J02 ranging from approximately 10−7 to 10−6 A/cm2, and 10−5 to 10−4 A/cm2, respectively. The objective of this experimental work is to investigate especially, the prospect of silicon /metal-oxide (Si/SnOx) based heterojunction to be used as optical sensors with tunable optoelectronic properties of SnOx.