An AlN photoconductor for X-ray detection has been fabricated,and its response to X-ray irradiation intensity is studied.The photoconductor has a very low leakage current,less than 0.1 nA at an applied voltage of 100 V in the absence of X-ray irradiation.The photocurrent measurement results clearly reveal that the photocurrent is proportional to the square root of the X-ray irradiation intensity,and under relatively high irradiation the photocurrent can reach values one order of magnitude larger than the dark current when a voltage of 100 V is applied across the AlN photoconductor.By using the ABC model the dependence of the photocurrent on the X-ray irradiation intensity is analyzed,and a reasonable interpretation of the physical mechanism is obtained.
Based on the principles of metal-semiconductor-metal Schottky barrier photodetectors（MSM-PD）, using the carrier rate equations,the circuit simulation model of a GaN-based MSM photovoltaic ultraviolet detector is constructed through an appropriately equivalent process.By using the Pspice analytical function of Cadence soft on the model,the relationship between the photocurrent and the terminal voltage under different UV light powers is analyzed.The result shows that under the given UV power,the photocurrent increases and tends to become saturated gradually as the terminal voltage of the device increases,and that under different UV powers,the photocurrent increases with increasing incident power.Then the analysis of the relationship between the photocurrent and the terminal voltage under the different ratios of interdigital electrode space and width is carried out when the UV power is given.The results show that when the ratio of interdigital electrode space and width（L/W） equals 1,the photocurrent tends to be at a maximum.
