The lateral photovoltaic effect in ITO/Si(n) heterojunction

The ITO/Si heterojunction has been studied as a solar cell longtime ago, but seldom done on the lateral photovoltaic effect (LPE). In this paper, we reported a new finding of lateral photovoltaic effect (LPE) in the ITO/Si(n) heterojunctions. The ITO films were prepared directly on the n-type single crystal Si substrate with different thicknesses by magnetron reactive sputtering technology. When we measured the lateral photovoltages in the ITO/Si structures as a function of laser position under illumination of different laser powers and different laser wavelengths, it was found that the LPE increased with both laser power and laser wavelength, which can be ascribed to the increased number of electron-hole pairs resulting from the increased laser power for a constant laser wavelength or the increased laser wavelength for a constant laser power. Moreover, the position sensitivity decreased dramatically with increasing the thickness of ITO thin films, but the nonlinearity seems to be improved gradually, both of which can be successfully explained by the increased carrier diffusion length induced by the decreased resistivity of ITO layer. The ITO/Si(n) heterojunction possesses good position sensitivity and suitable nonlinearity simultaneously when the thickness of ITO layer is 15 nm. Our results may provide important insight that one can obtain a suitable LPE in the ITO/Si(n) heterojunction with higher position sensitivity and lower nonlinearity by controlling the thickness of the ITO thin films, and also suggest that the ITO/Si(n) heterojunction is a potential candidate for developing novel and multifunctional optical sensors.