Low Temperature Synthesis of 2D p-Type α-In2 Te3 with Fast and Broadband Photodetection

Abstract

2D $A_2^{\mathrm{III}}{B}_3^{\mathrm{VI}}$ compounds (A = Al, Ga, In, and B = S, Se, and Te) with intrinsic structural defects offer significant opportunities for high-performance and functional devices. However, obtaining 2D atomic-thin nanoplates with non-layered structure on SiO₂ /Si substrate at low temperatures is rare, which hinders the study of their properties and applications at atomic-thin thickness limits. In this study, the synthesis of ultrathin, non-layered α-In₂ Te₃ nanoplates is demonstrated using a BiOCl-assisted chemical vapor deposition method at a temperature below 350 °C on SiO₂ /Si substrate. Comprehensive characterization results confirm the high-quality single crystal is the low-temperature cubic phase α-In₂ Te₃ , possessing a noncentrosymmetric defected ZnS structure with good second harmonic generation. Moreover, α-In₂ Te₃ is revealed to be a p-type semiconductor with a direct and narrow bandgap value of 0.76 eV. The field effect transistor exhibits a high mobility of 18 cm² V^-1 s^-1 , and the photodetector demonstrates stable photoswitching behavior within a broadband photoresponse from 405 to 1064 nm, with a satisfactory response time of τ_rise = 1 ms. Notably, the α-In₂ Te₃ nanoplates exhibit good stability against ambient environments. Together, these findings establish α-In₂ Te₃ nanoplates as promising candidates for next-generation high-performance photonics and electronics.

Keywords: SHG generation; chemical vapor deposition; fast and broadband photodetection; low temperature synthesis; α-In2Te3.