Low-Temperature Deposition of Layered SnSe₂ for Heterojunction Diodes

Tin diselenide (SnSe₂) has been recently investigated as an alternative layered metal dichalcogenide due to its unique electrical and optoelectronics properties. Although there are several reports on the deposition of layered crystalline SnSe₂ films by chemical and physical methods, synthesis methods like pulsed laser deposition (PLD) are not reported. An attractive feature of PLD is that it can be used to grow 2D films over large areas. In this report, a deposition process to grow stoichiometric SnSe₂ on different substrates such as single crystals (Sapphire) and amorphous oxides (SiO₂ and HfO₂) is reported. A detailed process flow for the growth of 2D SnSe₂ at temperatures of 300 °C is presented, which is substantially lower than temperatures used in chemical vapor deposition and molecular beam epitaxy. The 2D SnSe₂ films exhibit a mobility of ≈4.0 cm² V⁻¹ s⁻¹, and are successfully used to demonstrate SnSe₂/p-Si heterojunction diodes. The diodes show I _on/I _off ratios of 10³–10⁴ with a turn on voltage of <0.5 V, and ideality factors of 1.2–1.4, depending on the SnSe₂ film growth conditions.