Photo-response Characteristics Of Molybdenum Disulfide Based On Two Dimensional Nanomaterials

Two-dimension semiconductor materials have attracted significant interest since their unique electrical and optical properties that cannot be obtained by bulk counter-parts.Atomic-thick MoS₂ has widely applied in photo-electrical devices since the strongest photon-MoS₂ interactions.Remarkable breakthroughs have been taken in photo-controllable and photodetector devices based on MoS₂ homo-/heterostructure re-cently.However,they still suffer from some issues such as low photo-responsibility and external quantum effective?EQE?.In this thesis,by means of surface modification above MoS₂ FETs,we proposed photo-controllable device that improve photo-responsibility and vertical heterejunction based photodiode that increase EQE,respectively.1.In chapter three,we focus on the photo response behavior of the annealed Au decorated TMDs FETs.We found the significant photo-induced doping when the device was illuminated by UV light.The doping concentration is as high as 10¹⁴ cm^-2,which reach the degenerated doping level in MoS₂ channel.The photo-induced doping mech-anism is confirmed by system electrical and optical test.In addition,the doping process is practicable on other TMDs materials.What's more,by applied this doping method,we have successfully improved the contact resistance in the interface of TMDs and electrode,and accomplished band-to-band tunneling based on homojunction device,which exhibits negative differential resistance?NDR?with peak to valley ratio of 3.1.2.The vertical heterostructure that consist of MoO₃/MoS₂ is investigated.The de-vice takes the advantage of all MoS₂ channel as photo response region.As a result,the high on/off ratio?10³?,high photo responsibility?1.34 A/W?and high EQE?300%?heterojunction based photodiode is demonstrated.Furthermore,the photo current of the heterostructure can be modulated by the gate voltage.