Lateral photovoltage in natural pyrite: Mechanism, model, and characteristic

• Establishing a model for the lateral photovoltage of natural pyrite based on trap effect and metal-semiconductor junction. • Lateral photovoltage between electrodes varies linearly with the laser position, while remains stable outside the electrodes. • Revealing the two-dimensional position response law of lateral photovoltage in natural pyrite. • Improving the response rate of lateral photovoltage in natural pyrite by the bias current. The organic, inorganic and impurity interactions in natural pyrite significantly affects the motion state of non-equilibrium charge carriers, resulting in differences in its lateral photovoltage (LPV) compared to conventional semiconductors. In this paper, the LPV of natural pyrite was studied to address the issues of incomplete LPV mechanism and unclear external factors. The generation, recombination, and diffusion mechanisms of photo generated carriers in natural pyrite were elucidated, and a theoretical model of LPV variation with irradiation time and position was established by the trap effect and Schottky barrier at the metal-pyrite contact. Under the irradiations of continuous and pulsed lasers, the LPV of natural pyrite is consistent with the fitting curve of the LPV theoretical model. When laser irradiates the surface electrode of natural pyrite, the Schottky barrier formed by the contact between metallic silver and pyrite enhances the LPV. When the laser irradiates the area between two electrodes, there is a linear relationship between LPV and the laser irradiation position, and the position sensitivity decreases with increasing electrode spacing, while the LPV does not change with the laser irradiation position outside of the electrode and the stable LPV value is positively correlated with the electrode spacing. The results of two-dimensional position response shows that LPV exhibits the linearity and saddle shaped dependences on the irradiation position along x and y directions, respectively. Furthermore, the bias current effectively improves the response rate of LPV. This study will enrich the foundation of the photoelectric effect of natural pyrite, and be expected to help reveal its role in geology and the origin of life.