The Epitaxy Of The Low-dimensional Heterostructures Based On PbS(Se) For Infrared Optoelectronic Detection

Low-dimensional semiconductor materials are widely utilized in the field of optical,electrical,and optoelectronic devices due to their high crystalline quality,significant quantum size effects and controllable geometry.In particular,low-dimensional semiconductor heterostructures further enhance the performance of devices such as memories,lasers,and photodetectors due to their built-in electric field.Infrared photodetectors play a dominant role in communications,military and aerospace.Low-dimensional material heterostructure is one of the effective ways to realize infrared detectors with small size,high performance and room temperature detection.The narrow band gap material PbX(S,Se)has a narrow direct band gap and a large infrared light absorption coefficient,which can be applied to infrared detection.However,the high thermal equilibrium carrier concentration of PbX(S,Se)and the low thermal conductivity make the detector based thereon have a large dark current and a significant thermal effect,which greatly affects its detection performance.The monolayer MoS2 has distinctive features such as a large direct band gap and an atomically smooth surface.By constructing a heterostructure of PbX(S,Se)and MoS2,the dark current of the photodetector can be largely reduced and the spectral response range can be extended to the infrared region.The main purpose of this paper is to prepare low-dimensional heterostructures based on PbX(S,Se),and to study the performance of infrared detectors and improve the detection index.In this paper,PbS/CdS and PbSe/MoS2 heterostructures were synthesized by chemical vapor deposition,and their epitaxial relationships,optoelectronic properties and properties of infrared photodetectors were studied.The main contents and results of this paper are as follows:(1)High-quality low-dimensional CdS nanobelts and monolayer MoS2 have synthesized by chemical vapor deposition.The surface of the CdS nanobelt is smooth with good crystallinity.It is proven by Raman,AFM and photoluminescence spectroscopy that MoS2 sheets have high crystallinity with a very smooth surface.(2)A PbS/CdS heterostructure was prepared by a vapor phase epitaxy method.The PbS nanowires are aligned on the surface of the CdS nanoribbons to form an array.Using this structure,a two-electrode photodetector was fabricated.Under the illumination of 980 nm laser with the power density of 50 mW/cm2,the maximum responsivity was 4.7 mA/W,and the detectivity was 1.5×106 Jones.Under the 2775 nm mid-infrared laser with the optical power density of 400 mW/cm2 irradiation,the maximum responsivity is 3.5 mA/W,and the detectivity is 6.67×105 Jones.It shows that the PbS/CdS heterojunction detector has good infrared detection performance.(3)The PbSe/MoS2 heterostructures have formed via van der Waals epitaxy.We have studied the variable temperature infrared emission spectrum of PbSe and found its band gap decreases with increasing temperature,which can further illustrate the positive temperature coefficient of PbSe.According to the TEM,the epitaxial relationship between PbSe nanoplates and MoS2 sheet is found to be(200)Pbse ||(1(?)00)MoS2 in plane.Photodetectors based on these heterostructures exhibit the responsivity and detectivity of 51 mA/W,4.4×106 Jones,respectively,under 1550 nm light illumination,at room temperature.The unique properties of PbSe/MoS2 heterojunctions endow it with great potential for next generation infrared photodetector.