High-Performance Broadband Photodetectors Based on <i>n</i>-MoS₂/p-Ge_0.9Sn_0.1 Heterojunctions

Abstract

P–N junctions are essential building blocks for electronic and optoelectronic devices and exhibit a wide range of applications in the field of photodetectors. In this work, high-performance self-powered photodetectors with spectral coverage ranging from the visible to near-infrared rrange (405–1310 nm) has been successfully fabricated by combining a p-type Ge0.9Sn0.1 thin film with an n-type multilayered molybdenum disulfide (MoS2) into a type-II band alignment. Benefiting from the great light absorption of the multilayer MoS2 and the high in-plane mobility of the moderate Sn-doped Ge0.9Sn0.1 film with a direct band gap, the constructed P–N heterojunction can effectively generate and separate the photogenerated carriers and lead to superior zero-biased photodetection performance. The device exhibited a fast response time of 200 μs, an ultralow dark current of ∼0.1 pA and high photoswitching ratio of ∼104. In addition, the maximum values of photoresponsivity and detectivity are calculated to be 462 mA/W and 2.3 × 1012 Jones, respectively. This work provides the new promising candidates for self-powered photodetectors toward broadband, fast speed, high sensitivity, and low power consumption.