Controlled growth of Sb2Te3 nanoplates and their applications in ultrafast near-infrared photodetection

This work presents a study on controlled growth of Sb2Te3 nanoplates via chemical vapor deposition and their potential applications in near-infrared photodetectors. The lateral size of the nanoplates is investigated by studying two main growth parameters: argon carrier gas flow rate and growth temperature. As the argon gas flow rate increases from 20 sccm to 60 sccm, the average lateral size of Sb2Te3 nanoplates gradually increases from 3.68 μm to 10.31 μm as the growth of Sb2Te3 nanoplate under lower argon gas flow rate is limited by the Sb2Te3 molecules delivered onto the substrate surface. In contrast, at a higher argon gas flow rate of 80 sccm, the average lateral size decreases to 8.77 μm due to the combined effect of a saturated substrate surface reaction rate and increased heat loss by convection. Similarly, the average lateral size of Sb2Te3 nanoplates progressively increases from 4.21 μm at a growth temperature of 400 °C to 10.31 μm at 410 °C, which could be ascribed to the limited reaction rate of active Sb2Te3 molecules/atoms on the substrate surface at lower growth temperature. The average size then saturates at 10.06 μm at 415 °C upon further increasing the growth temperature as the growth of Sb2Te3 nanoplates is limited by the amount of vaporized Sb2Te3 molecules delivered onto the substrate surface. The fabricated photodetector based on Sb2Te3 nanoplates presents a wide spectral response from 400 to 980 nm, with a maximum photo-response observed at 850 nm. Notably, the photo-response time of the Sb2Te3 nanoplate photodetector is measured as small as 64 μs, indicating its ultrafast photo-response characteristics. The photodetector also exhibits good performance with a responsivity of 155.6 mA W−1 and a specific detectivity of 1.68 × 109 Jones at 850 nm with a light power intensity of 130.0 mW cm−2.