Phase-defined growth of In2Se3 thin films using PLD technique for high performance self-powered UV photodetector

Self-powered photodetectors have attracted enormous attention for their high sensitivity, fast response with low power consumption. The unique set properties defined for various polymorphs of In2Se3 offers wide range of potential applications for optoelectronic and memory devices. Here, three phases of In2Se3 including, layered alpha-In2Se3 and beta-In2Se3, and non-layered gamma-In2Se3, are grown using pulsed laser deposition (PLD) technique. Deposition gas pressure is found to govern the formation of In2Se3 phases attributed to flux of Se atoms reaching the heated substrate. Band structure, density of states and work function for each phase is calculated using first principles calculations to understand their electronic properties. Based on the obtained work functions, it is found that Schottky junction based ultraviolet photodetectors using as grown In2Se3 films exhibit high performance with photo-responsivity of 1310 mA/W for alpha-In2Se3, 260 mA/W for beta-In2Se3 and 240 mA/W for gamma-In2Se3 in self-powered mode under an illumination of ultraviolet radiation. The obtained high self-powered photodetection is attributed to the non-centrosymmetric structure of alpha-In2Se3 and gamma-In2Se3, which produce a built-in field due to in-plane spontaneous polarization. Thus, In2Se3 based self-powered photodetector prepared using PLD technique pave the way for low power optoelectronic device applications, environmental monitoring and military applications.