Research On Performance Of 4H-SiC Hot-electron Photodetector Based On Titanium Nitride Surface Plasmon Polaritons Effect

Vertical structure metal-semiconductor-metal（MSM）photodetectors have been widely used in communication,sensing,guidance,imaging,and environmental detection due to their low dark current,fast response speed,and ease of integration.and as a member of third-generation semiconductor silicon carbides（Si C）,4H-Si C,due to its higher thermal conductivity,melting point,stronger critical breakdown electric field and higher electron mobility than silicon（Si）,can replace silicon to achieve photodetection in some harsh environments.However,4H-Si C has a wide band gap,and the high cost of epitaxial process limits the choice of its application scenarios.The vertical structure MSM photodetector is directly prepared by the intrinsic type 4H-Si C,which reduces the fabrication cost of the device.The interface layer is deposited by atomic layer deposition（ALD）technology to make up for the Fermi level of the intrinsic type 4H-SiC that is clamped by the surface state.energy level,the defect that the device performance cannot be controlled by metal selection.Using Surface Plasmon Polaritons（SPP）hot electron effect is an excellent solution to broadening the detection spectrum of 4H-Si C photodetectors,but traditionally excited SPP mostly uses Au,a noble metal,but its cost is high.The SPP effect excited by titanium nitride（Ti N）is similar to that of Au,and compared with Au,its cost is lower and its plasmon resonances are tunable owning to their nonstoichiometry and large dependence in fabrication conditions,so it can be used in thermionic photodetectors instead of Au.Ti N was patterned using polystyrene（PS）nanospheres to realize full-spectrum photodetectors based on 4h-Si C and SPP hot hot electron effect.Reasonable control of the interfacial layer thickness and Ti N nanostructure size is the key to obtain high-performance full-spectrum Si C hot-electron photodetectors.（1）First,a vertical structure metal-semiconductor-metal（MSM）photodetector was prepared based on intrinsic 4H-Si C,using Ti N and metal as electrodes,and the possibility of using Ti N to replace metal was verified.The material and thickness were studied,and the Al₂O₃ film prepared by atomic layer deposition was added to suppress the dark current of the device to enhance the weak light detection capability of the device,and the optimal device performance was obtained based on the intrinsic type 4H-Si C.Then,PS nanospheres were used to introduce Ti N-NPs on 4H-Si C to explore the influence of the introduction on the optimal intrinsic device performance based on Ti N electrodes,and to characterize the optical and electrical properties after introduction.The thickness adjustment optimizes the optical and electrical properties of the photodetector,and finally the device is obtained in the composite based on SiC/TiN nanostructure,which broadens the response of SiC hot electron photodetection from the ultraviolet band to the visible and near-infrared band.Compared with the device without Ti N nanostructures,the optical performance of the device in the 400-900 nm band has been improved from almost 0 to more than 30%,and the photocurrent in the 660/850/980/1310 nm has increased.External quantum efficiency（EQE）,responsivity（R）and detection rate（D*）are improved by more than 30 times at 660nm.（2）On the basis of the above work,the TiN-NPs were replaced with PS nanospheres/Ti N composite nanostructures,the interface layer was removed,and another vertical structure MSM type 4H-Si C hot electron photodetector was prepared.The ultraviolet,visible and near-infrared bands from 300 to 900 nm all show good performance,and it can reach a high detection rate of 10¹² Jones in the ultraviolet band.In the 380nm～800 nm spectral range,its D*is always maintained at the order of 10¹¹ Jones,which is always higher than the standard device by 1 order of magnitude or more,and after 500 nm,it is always higher than the standard device by more than 3 orders of magnitude.In the near-infrared band of 800～900 nm,the device reaches the cut-off wavelength,but the D*still reaches 10¹⁰ Jones at 850 nm,and even in the band after 900 nm,it still has a D*of more than 10⁹ Jones,showing excellent spectral broadening ability and wide Spectral detection capability.