Low Temperature Synthesis of 2D p-Type α-In₂Te₃ with Fast and Broadband Photodetection

2D (Formula presented.) 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-In₂Te₃ 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-In₂Te₃, possessing a noncentrosymmetric defected ZnS structure with good second harmonic generation. Moreover, α-In₂Te₃ 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-In₂Te₃ nanoplates exhibit good stability against ambient environments. Together, these findings establish α-In₂Te₃ nanoplates as promising candidates for next-generation high-performance photonics and electronics.