High-performance MoSphototransistors with HfAlO back-gate dielectric layer grown by plasma enhanced atomic layer deposition.

Molybdenum sulfide (MoS) as an emerging optoelectronic material, shows great potential for phototransistors owing to its atomic thickness, adjustable band gap, and low cost. However, the phototransistors based on MoShave been shown to have some issues such as large gate leakage current, and interfacial scattering, resulting in suboptimal optoelectronic performance. Thus, Al-doped hafnium oxide (HfAl) is proposed to be a dielectric layer of the MoS-based phototransistor to solve this problem because of the relatively higher crystallization temperature and dielectric constant. Here, a high-performance MoSphototransistor with HfAlO gate dielectric layer grown by plasma-enhanced atomic layer deposition has been fabricated and studied. The results show that the phototransistor exhibits a high responsivity of 2.2 × 10A W, a large detectivity of 1.7 × 10Jones, a great photo-to-dark current ratio of 2.2 × 10%, and a high external quantum efficiency of 4.4 × 10%. The energy band alignment and operating mechanism were further used to clarify the reason for the enhanced MoSphototransistor. The suggested MoSphototransistors could provide promising strategies in further optoelectronic applications.