High sensitivity and fast response infrared detector fabricated with the Bi2Se3-PbSe heterojunction

A heterojunction photodetector based on the photogating effect is fabricated by combining the novel topological insulator Bi2Se3 with the traditional narrow-gap PbSe. The Bi2Se3-PbSe heterojunction is constructed by depositing PbSe thin film on surface of Bi2Se3 with the molecular beam epitaxy technique. Large lattice mismatch between cubic PbSe and rhombohedral Bi2Se3 is relaxed through the van der Waals epitaxial growth process, leading to an atomically abrupt and smooth Bi2Se3-PbSe heterointerface. Benefiting from the prominent photosensitivity in narrow-gap PbSe and the ultrafast charge transport in topological insulator Bi2Se3, high photosensitivity and fast response are simultaneously observed in the as-fabricated photodetectors. Responsivity and detectivity are 31.4 AW−1 and 1.7 × 1011 cmHz0.5 W−1 respectively. Rising and falling time are 240 μs and 500 μs respectively. In this structure, the appropriate band alignment of Bi2Se3-PbSe heterojunction and the photogating effect could synergistically utilize the advantages of both Bi2Se3 and PbSe, suggesting a potential solution to broaden the application prospect for both sides.