Electrical and photovoltaic characteristics of MoS₂/Si p-n junctions

Bulk-like molybdenum disulfide (MoS₂) thin films were deposited on the surface of p-type Si substrates using dc magnetron sputtering technique and MoS₂/Si p-n junctions were formed. The vibrating modes of E¹_2g and A_1g were observed from the Raman spectrum of the MoS₂ films. The current density versus voltage (J-V) characteristics of the junction were investigated. A typical J-V rectifying effect with a turn-on voltage of 0.2 V was shown. In different voltage range, the electrical transporting of the junction was dominated by diffusion current and recombination current, respectively. Under the light illumination of 15 mW cm⁻², the p-n junction exhibited obvious photovoltaic characteristics with a short-circuit current density of 3.2 mA cm⁻² and open-circuit voltage of 0.14 V. The fill factor and energy conversion efficiency were 42.4% and 1.3%, respectively. According to the determination of the Fermi-energy level (∼4.65 eV) and energy-band gap (∼1.45 eV) of the MoS₂ films by capacitance-voltage curve and ultraviolet-visible transmission spectra, the mechanisms of the electrical and photovoltaic characteristics were discussed in terms of the energy-band structure of the MoS₂/Si p-n junctions. The results hold the promise for the integration of MoS₂ thin films with commercially available Si-based electronics in high-efficient photovoltaic devices