Fabrication And Investigation Of The Heterojunction Detectors Of CuI Films By Vacuum Heat Evaporation

Cuprous iodide?CuI?is a p-type direct wide-band gap inorganic semiconductor material with band gap width of 3.1eV,high exciton binding energy?62meV?,high carrier concentration and high hole mobility.Moreover,CuI is rich in reserves,cheap in price,non-toxic and pollution-free,and has a high transmittance in the visible wave band.However,in order to prepare high performance optoelectronic devices,high quality CuI films are needed.Although there are many methods for preparing CuI films,the quality of the CuI films is generally lower.In order to prepare high quality thin films,CuI thin films were prepared by vacuum hot evaporation coating technology and and optimized growth process,which provided a basis for the study of their characteristics and the application of optoelectronic devices.And ZnO films and high quality ZnO nanowires were prepared by pulsed laser deposition?PLD?and high-pressure pulsed laser deposition?HP-PLD?,the high quality TiO₂ nanorods were prepared by hydrothermal synthesis.The p-CuI/n-ZnO film heterojunction,p-CuI/n-ZnO nanowires heterojunction and p-CuI/n-TiO₂ nanorods heterogeneous ultraviolet detection were constructed with CuI film respectively.And photoelectric characteristics of the three detectors are studied respectively.This paper mainly carries out the following research:1.CuI thin films were prepared by high vacuum thermal evaporation technology and the preparation process was optimized.The morphology,structure and luminescence characteristics of CuI films were studied.Photopoluminescence?PL?spectroscopy shows that under the condition of substrate unheated,the XRD results show that CuI thin films are polycrystalline stone-cui with high?111?crystal phase preference,and the crystal quality of CuI thin films increases with the increase of substrate temperature at room temperature to 100?.Moreover,the crystal quality of CuI thin films prepared on Si slices is higher than that on quartz substrate.When the substrate heating temperature is 100?,the crystallization quality is the best.In addition,the average transmittance of thin films with thickness of?250nm in the visible light band is?79.15%,and the maximum transmittance is?91.9%.2.The ZnO thin film and nanowires were prepared on Si substrate by ultra-high vacuum PLD technology and metal-free high pressure PLD technology.The morphology,structure and luminescence characteristics of ZnO thin film and nanowires were studied.The results of scanning electron microscopy and X-ray diffraction show that when the temperature was 650?and the pressure was 4.0×10⁴Pa,the ZnO nanowires prepared had the best crystal quality and grew optimously along the crystal direction of?001?.The average diameter of a single nanowire was about 80nm and the length can be controlled within 2?m?5?m.3.The p-CuI/n-ZnO film heterojunction ultraviolet detector was constructed.Heterojunction ultraviolet detector was constructed by deposition of CuI film on the ZnO film prepared by PLD.And it has good diode rectification characteristics,the switching ratio is about 45.1.Under the illumination of 400nm and the bias voltage of-5V,the peak response is about 0.02A/W,and the maximum detection rate is 1.54×10¹¹cmHz^1/2/W,the response time was 81.6ms and the recovery time was 92.9ms.4.The p-CuI/n-ZnO nanowires heterojunction ultraviolet detector was constructed.The nanostructured heterojunction ultraviolet detector was constructed by depositing CuI on ZnO nanowires array.The heterojunction device has better diode rectification characteristics,with a switch ratio of up to 5500 times,and a switch ratio of?122times higher than that of ZnO thin film heterojunction.Under the illumination of385nm and the bias voltage of-5V,the peak response is about 0.235A/W,and the maximum detection rate is 1.23×10¹²cmHz^1/2/W,compared with CuI/ZnO thin film heterojunction devices,they were enhanced by?12 and?8 times,respectively.In addition,the detector's peak response wavelength is blue shifted?370nm-400nm?,which makes the heterojunction detector more repeatable and stable.5.The p-CuI/n-TiO₂ nanorods heterojunction ultraviolet detector was constructed.TiO₂ nanorods were grown by hydrothermal synthesis method,and the UV detector of nanostructured heterojunction was constructed with CuI,with the maximum switching ratio?31.1 times,.Under the illumination of 385nm and the bias voltage of-5 V,the peak response is about 0.232A/W,and the maximum detection rate is 5.515×10¹¹cmHz^1/2/W,at the same time,it has a fast response speed.The one-dimensional TiO₂nanostructure has a large specific surface area,which can increase the contact area with CuI to improve the light utilization rate and provide more ways for the transport of photogenic carriers,so as to improve the photoelectric performance of heterojunction detectors.