The Preparation And Performance Studies Of 4H-SiC Schottky Barrier Alpha Particle Radiation Detector

Nuclear radiation detection technology has important applications in space exploration,national defense security,medical imaging,food inspection and so on.Semiconductor nuclear radiation detectors have many advantages,such as small size,simple structure,high detection efficiency,fast response speed and high energy resolution.These advantages make it be widely used in various nuclear radiation detection systems.Traditional semiconductor radiation detectors need to work under low temperature conditions,the device performance is easily affected by the ambient temperature and radiation intensity,which can't keep working for a long time in high temperature and strong radiation harsh environments.Silicon carbide is the wide band-gap semiconductor material which has many excel ent properties,such as high thermal conductivity,high thermal stability,and large critical displacement energy.It's suitable for the fabrication of high-temperature and radiation-resistant detector which is light,low power consumption and stable detection performance.In this paper,the Au/Ni/4H-SiC Schottky barrier detectors were designed and fabricated.The effect of thermal stability and field plate structure on the electrical properties and alpha particle detection performance of the detector was investigated.The Au/Ni/N 4H-SiC Schottky barrier alpha-particle detectors were annealed between 400°C and 700°C to investigate the effect of thermal stability of the Schottky contact on the structural and electrical characteristics of the detectors.At the annealing temperature of 500°C,two different nickel silicides(i.e.,Ni₃₁Si₁₂ and Ni₂Si)were formed at the interface and resulted in the formation of inhomogeneous Schottky barrier.With the increase of the annealing temperature,the Ni₃₁Si₁₂ transformed into the more stable Ni₂Si and formed a uniform Schottky barrier.During the reaction,the barrier height and reverse leakage current changed with the annealing temperature.At the annealing temperature of 600°C,the barrier height was 1.55eV and leakage current density was 1.83 nA/cm² at the reverse voltage of 50V.The reduction of the leakage current can decrease the noise interference to energy resolution of detectors.Therefore,the detector annealed at 600°C has a better energy resolution of 2.60%for 5.48MeV alpha-particles.The experimental results show that the detectors after thermal treatment up to 700°C still has good electrical properties and detection performance.Finally,the Au/Ni/N 4H-SiC Schottky barrier alpha-particle detectors with field plate structure were fabricated and studied.The experimental results show that the 4H-SiC detectors with field plate structure can effectively reduce the electric field concentration effect at the Schottky junction edge and decrease the reverse leakage current of the detector.Parts of the?particles incident the SiO₂ layer and sensitive area with a certain angle,more alpha-particle energy is lost in the dead layer and has no contribution to the output pulse amplitude,which results in the broadening of the energy spectrum.At the same time,the capacitance of 4H-SiC detectors gradually increases with the field plate length and the signal-to-noise ratio of the test system decreases,which results in the degeneration of energy resolution.When the field plate length is 0.75mm,the 4H-SiC detector has a better resolution of 4.00%for 5.48MeV alpha-particle.