Study On Preparation And Photoresponse Performance Of 2d Bi Films On Rigid And Flexible Substrates

In the present,two-dimensional?2D?materials have attracted widespread research attention due to their excellent electrical and optoelectronic performances.The research areas of 2D?two-dimensional?materials are extremely abundant,including graphene,black phosphorus?BP?,hexagonal boron nitride?h-BN?,transition-metal dichalcogenides?TMDs?and topological insulators?TIs?etc.In the future,the superior photodetectors with high-responsivity,ultra-broadband,self-powered and flexibility will serve as indispensable part of ingenious optoelectronic devices.On the one hand,researchers tend to develop the self-powered?self-driven?photodetectors,which work at zero bias voltage without consuming other external power.On the other hand,flexible optoelectronic devices have drawn huge attentions because of their potential applications in foldable displays,curved digital phones,and other flexible electronic systems.Bi?Bismuth?film,as a novel-innovative topological insulator material,is made of Bi atoms in the family of group VA.It possesses optical activity.In the meantime,Bi is internally insulating but its surfaces have highly conductive characteristics.The relatively small bulk band gap of Bi guarantees its ultra-broadband photo-response.The main research purpose of this thesis is to systematically investigate growth and the preparation of Bi films on the rigid?300 nm Si O₂/Si?and flexible?polyimide?substrates,morphology characterization,Optical response characteristics of Bi films are further studied to improve the film quality and to explore potential application in photodetections.The main experimental research content is as follows:?1?Growth of Bi films was successfully achieved on the rigid?300nm Si O₂/Si?and flexible polyimide?PI?substrates through vapor deposition method.The conditions such as temperature?T?,pressure?P?and carrier gas flow rate?SCCM?in the growth process of Bi?bismuth?were regulated,and the Bi films were characterized to complete the controllable preparation of Bi films.?2?A rigid photodetector was constructed by using Bi films grown on Si O₂/Si substrate.The photocurrents of the photodetector were measured with five different laser power as the incident light sources?405 nm,660 nm,808 nm,980 nm and 1064 nm,respectively?as well as setting the various bias voltages and adjusting the light power.The I-V and the photo-switching characteristics showed that the rigid device has an ultra-broadband photo-response range in the range of visible light?VIS?to near infrared ray light?NIR?wavelengths.Furthermore,it showed fast,highly stable and self-powered photo-responses.?3?A flexible photodetector was constructed by using Bi films grown on PI substrate.The photo-response performances of the flexible photodetector were investigated.The photocurrent of the photodetector was measured with a visible laser?660 nm?and a near NIR laser?808 nm?under various bias voltages and curvature radius.The study found that after hundreds of bending cycles,the flexible device still exhibits good durability and reproducibility in photo-switching and I-V characteristics...