| In recent years,infrared photodetectors have achieved rapid development,and their applications have gradually spread from military areas into all aspects of our lives,such as temperature measurement and epidemic prevention,motion detection,optical communication,chemical sensing,search and rescue,and so on.These increased functional applications raise new requests for infrared detection,which are further realizing room-temperature,high-performance,high-sensitivity,wide-spectrum,small and low-cost infrared photodetectors.At this time,due to their special structures and physical characteristics,low-dimension materials have attracted more and more scholars'attention.Among these,nanowires have small size,abundant surface states,superior specific surface area and so on,which show great potential in photodetectors and are expected to play an important role as channel materials in next-generation optoelectronic devices.In this paper,recent advances in semiconductor nanowires infrared photodetectors were investigated in details and the main issues to hinder the development of infrared detection technology are found,which are excessive dark current and noise interference.Based on these problems,many research works have been carried out and attained a lot of achievements.Among these,controlling surface states or constructing core-shell structures of nanowires have an effect on reducing dark current and improving infrared detection performance.Therefore,this paper is mainly devoted to the synthesis of semiconductors with abundant surface states or core-shell structures for infrared detection,and the researches of surface states or core-shell structures for nanowires infrared photodetectors.After further investigations,III-V group semiconductors.are suitable for infrared detection due to their narrow bandgap and high carrier mobility,and are favorable mode in this paper due to their natural oxide layer and abundant surface states.Among these,on the surface of In As and GaAs nanowires,there are natural oxide shells and the near-surface-depletion caused by the oxide layer will lead to their ambipolar transport behaviors.And the dark current of the nanowires will decrease to a certain extent due to low-energy defects in oxide layer.Combining the characteristics of InAs and GaAs nanowires,therefore,ternary alloy InGaAs nanowires are prepared to study the infrared detection applications of the oxide layer-induced ambipolar nanowires in details in this paper.The content is as follows.Firstly,ternary alloy InGaAs nanowires were prepared by a simple Ni-catalyzed solid source chemical vapor deposition method,and the prepared nanowires was determined to be In0.2Ga0.8As with the band gap of 1.28 eV by morphology characterization,composition analysis and optical characterization.Then,the single nanowire field effect transistor(FET)was fabricated,and an ambipolar conduction behavior was observed.Confirmed by oxidation experiment and micro-structure characterization,the ambipolar transport was caused by the native surface oxide shell.Based on above,under 850 nm laser illumination,the fabricated ambipolar nanowire FETs show extremely low dark currents of 50 pA and 0.5 pA,as well as corresponding maximal responsivities of 53 mA·W-1 and 283 mA·W-1 when positive and negative gate voltages are applied,respectively.Besides,based on the chemical vapor deposition technology of InGaAs nanowires,InGaAs nanowires were prepared on slides substrates in the same way successfully.In conclusion,the surface states or core-shell structures of nanowires(caused by oxide layer in this paper)have a unique design and control function in infrared detection,which are important parameters of next-generation optoelectronic devices.In addition,the successful preparation of nanowires on low-cost substrates has greatly reduced the preparation cost of materials,which is of great significance in realizing the wide range of applications of nanowires in the future. |
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