3D Band Diagram and Photoexcitation of 2D–3D Semiconductor Heterojunctions

• DOI: 10.1021/acs.nanolett.5b02012
• Publication Date: 2015-08-17T13:57:12Z
• Authors: Bo Li; Gang Shi; Sidong Lei; Yongmin He; Weilu Gao; Yongji Gong; Gonglan Ye; Wu Zhou; Kunttal Keyshar; Ji Hao; Pei Dong; Liehui Ge; Jun Lou; Junichiro Kono; Robert Vajtai; Pulickel M. Ajayan
• Keywords: Photoexcitation; Band diagram

The emergence of a rich variety two-dimensional (2D) layered semiconductor materials has enabled the creation atomically thin heterojunction devices. Junctions between 2D layers and 3D bulk semiconductors can lead to junctions that are fundamentally electronically different from covalently bonded conventional junctions. Here we propose new band diagram for formed n-type monolayer MoS2 p-type Si, in which conduction valence band-edges drawn both stacked in-plane directions. This helps visualize flow charge carriers inside device manner. Our detailed wavelength-dependent photocurrent measurements fully support diagrams unambiguously show alignment is type I this 2D-3D heterojunction. Photogenerated electron-hole pairs separated driven by an external bias control "on/off" states junction photodetector device. Two photoresponse regimes with fast slow relaxation also revealed time-resolved measurements, suggesting important role played trap states.