Preparation Of NiO/SiC Junctions By Sol-gel Method And Research Its Photoelectric Properties

As a transition metal oxide,NiO is a natural P-type wide band gap semiconductor which the band gap width is between 3.6eV and 4.0eV at room temperature.It is currently widely used in detectors,solar cells,gas sensors,electrochromism and other fields.In order to solve the problem of low p+n emitter junction injection efficiency due to incomplete ionization of P-type SiC in silicon carbide bipolar power devices,this study considers the use of P-type NiO and N-type SiC to form a heterojunction as Emit the junction to improve the injection efficiency of the junction.In this paper,based on the sol-gel method,NiO thin film preparation and lithium doping technology are studied,and the static and dynamic photoelectric characteristics of the NiO/SiC heterojunction formed on the 4H-SiC substrate are experimentally studied.The main work and research results are as follows:1.The NiO film was successfully prepared by sol-gel method and the effects of Ni2+concentration,annealing temperature and annealing time on the surface morphology,grain size,optical transmittance and optical band gap of NiO film were studied.When the sol concentration was 0.5mol/L,the annealing temperature was 500?,and the annealing time at 1h,the surface of the c characteristics of the heterojunction were analyzed.The results show that the heterojunction exhibits good rectification characteristics in the dark state.When the applied bias voltage is±8V,the rectification ratio can reach 81,and the turn-on voltage of the heterojunction is around 3.0V.When the applied bias voltage is-7V,and the heterojunction is irradiated with ultraviolet light with a wavelength of 365nm and an optical power density of 340mW/cm2,the optical responsivity of the heterojunction is 2.94mA/W,and the specific detection rate is 2.0×1011 Jones,the switch ratio is 1474.4.The transient photoelectric characteristics of the heterojunction are studied.It is found that when the wavelength of the heterojunction is 365nm,the optical power density is 340mW/cm2 ultraviolet light irradiation,the rise time of heterojunction ?r?19.1ms,the fall time?f=87.8ms.