High-ZT materials and high-performance devices have always been hot topics in the field of thermoelectric applications. Here we present a field effect transistor (FET) based method to optimize the thermoelectric properties of bismuth telluride thin films, by which Seebeck coefficient, electrical conductivity and carrier type of the films are continuously controllable. As a result, the maximum power factor of the sample reaches 14.9 µWcm⁻¹ K⁻² in N-type and 12.5 µWcm⁻¹ K⁻² in P-type at room temperature. As compared with the bulk, the thermal conductivity of the bismuth telluride thin film is greatly reduced, which is measured to be lower than 0.37 Wm⁻¹ K⁻¹. The actual ZT of the sample exceeds 1.22 in N-type and 1.02 in P-type at 303 K, respectively. A π-shaped in-plane N-P pair device was built by applying different gate voltage on the bismuth telluride thin films at the two legs, which open circuit voltage is 10.5 mV and the maximum output power is 10.3 nW at a temperature difference of 30 K. By using the Te-doped bismuth telluride thin films, the intrinsic carrier concentration of the sample decreases to 1.05 × 10¹⁷/cm³ (N-type) and the films can be tuned into N-type and P-type by the opposite gate voltage symmetrically. Using this material, a thin film thermocouple with a quasi-linearly adjustable sensitivity from 2.4 to 225.5 µVK⁻¹ by voltage was obtained. This work provides a general method to obtain high-ZT of thermoelectric materials and new ideas for fabricating performance controllable device with the same thermoelectric material, which greatly simplifies the material growth process in device manufacturing.

高ZT材料和高性能器件一直是热电应用领域的热门话题。在这里，我们提出了一种基于场效应晶体管 (FET) 的方法来优化碲化铋薄膜的热电性能，通过该方法可以连续控制薄膜的塞贝克系数、电导率和载流子类型。结果，样品的最大功率因数在室温下在N型中达到14.9μWcm ^-1 K ^-2，在P型中达到12.5μWcm ^-1 K ^-2。与块体相比，碲化铋薄膜的热导率大大降低，实测低于0.37 Wm ^-1 K ^-1. 在 303 K 时，样品的实际 ZT 在 N 型中分别超过 1.22 和在 P 型中超过 1.02。通过在两条腿的碲化铋薄膜上施加不同的栅极电压，构建了一个π形面内NP对器件，开路电压为10.5 mV，最大输出功率为10.3 nW，温差为30 K . 通过使用掺Te碲化铋薄膜，样品的本征载流子浓度降低到1.05×10 ¹⁷ /cm ³ (N型)，薄膜可以通过相反的方式调谐成N型和P型栅极电压对称。使用这种材料，薄膜热电偶具有从 2.4 到 225.5 µVK ^-1的准线性可调灵敏度通过电压得到。该工作提供了一种获得高ZT热电材料的通用方法和用相同的热电材料制造性能可控器件的新思路，大大简化了器件制造中的材料生长过程。