Preparation And Properties Of Photodetector Based On Molybdenum Disulfide

Since graphene was discovered,two-dimensional materials have attracted great attention from researchers.Molybdenum disulfide（Mo S₂）is a representative of transition metal chalcogenide compounds,has a band gap of about 1.2e V in Mo S₂ body material,while that of monolayer is about 1.9e V.As a narrow-band semiconductor,the band gap of Mo S₂ body material changes with the number of layers.Mo S₂ has good light absorption from visible to near infrared wavelengths.Due to its excellent optical and electrical properties,it has great potential in the preparation of photodetectors.First of all,we prepared Mo S₂ thin films of different thickness according to magnetron sputtering,the surface of the thin films is uniform,the crystal condition is good,and the heterojunction photodetector with Ga As is formed.The test shows that the performance of the device is optimal when the sputtering time is 20min and the thickness of Mo S₂ thin film is about 300nm,and the photodetector made has obvious photovoltaic effect.Under the illumination with wavelength of 650nm and power of 5.1m W,the responsivity and detection rate of the device reach 0.107AW^-1 and 3.13×10¹¹Jones.The short-circuit current of the device is 1×10^-6A and the open-circuit voltage is 0.1V,indicating that the device has good self-driving ability.The rise time and fall time are 485ms and 501ms,respectively.Meanwhile,the device has a good optical response,with obvious photocurrent generated at wavelengths from 405nm to 980nm,indicating that this heterostructure with vertical structure has good photoelectric performance.Due to the excellent photoelectric performance of MXene material,according to its characteristics,we simply drop it on the surface of Mo S₂ film to form Schottky junction,while Mo S₂ film grows on the surface of ITO glass.When light is irradiated from different surfaces on Mo S₂/MXene interface,the effect is different.Therefore,we prepared two kinds of devices:The first is light irradiated from MXene surface,and the second is light irradiated from Mo S₂surface.Under the illumination wavelength of 650nm and power of 20m W,the responsivity and detection rate of the two devices are 0.050AW^-1,4.4×10¹⁰Jones and 0.074AW^-1,3.1×10¹⁰Jones,respectively.The second structure also has a certain self-driving ability.Under illumination conditions,it has a short circuit current of 1×10^-5A and an open circuit voltage of2×10^-4V.