Controllable Growth Orientation Of Tin Disulfide Layer Material And Investigation Of The Optoelectronic Devices

The planar semiconductor device fabrication techniques promoted us to control the growth orientation of layered metal dichalcogenide materials. In this dissertation, we demonstrated an efficient approach to control the growth orientation of tin disulfide(SnS2) and the applications in phototransistors. The related points were summarized as followed:(1) The in-plane and vertical growth of SnS2 could be mediated by adopting different substrates. In-plane SnS2 was successfully grown on two-dimensional(2D) substrates(mica, graphene, etc.) due to the van der Waals epitaxial growth. And the vertical SnS2 grown on three-dimensional(3D) substrates was attributed to the impeding effect of dangling bonds. The secondary growth control experiments were carried out and the growth results further verified our explanations.(2) The in-plane SnS2 was further applied in back-gated phototransistors. The field-effect mobility and current on/off ratio of back-gated field-effect transistors(BG-FETs) reached 4 cm2 V-1 s-1 and 105. The as-grown SnS2 phototransistors showed small photoswitching ratio(~1.3), large dark current(~?A) and slow response time(~second order). The sluggish response was ascribed to long-lived traps which might be induced by sulfur vacancy defects(VS).(3) The as-grown samples were further annealed in saturated sulfur atmosphere. The treatment could greatly suppress the deteriorating effect of long-lived traps. The corresponding photoswitching ratio, dark current and photoresponse time were improved to ~40, pA and millisecond order, respectively. The controllable orientation growth and efficient treatment technique were expected to be widely applied in other 2D metal dichalcogenide materials for high-performance optoelectronic devices.