Preparation And Properties Of Radiation Schottky Detector At The Room Temperature Based On Epitaxial N-GaN Film

As the representative of the third generations of semiconductor material, Gallium Nitride (GaN) and its multi-alloy materials with excellent optical and electrical properties, have a potentional application in short wavelength optoelectronic devices and high temperature, high power, high-speed microelectronic devices and other fields. Currently, a variety of GaN-based detectors, especially solar blind UV detectors and nuclear radiation detectors have become a new hotspot. Since GaN has wide band gap, strong covalent bonding, high melting point, high breakdown electric field, anti corrosion, and high radiation resistance. And, in the area of strong radiation detection, with the growing intensity of the radiation sources, conventional Si detectors can not work at such a high radiation field. So, the study of GaN Schottky barrier radiation detectors'preparation and properties is significant.In this paper, Radiation Schottky detector at room temperature based on epitaxial n-GaN film was made. The n-GaN ohmic contact was researched, including the alloying method, surface treatment and annealing process. We use Ti (20nm)/Al (20nm)/Ti (20nm)/Au (300nm) alloys and several surface treatments, and find that the most useful method is ICP etching with a specific contact resistivity of 3 x 10-8(O·cm2); the second one is the hydrochloric acid:hydrofluoric acid:water (HCl:HF:H2O= 1:1:10) method with a specific contact resistivity of 1.1×10-7 (O·cm2). Ohmic contacts become worse after annealing.In this paper, we use Double Schottky Contact method, researching the contact characteristics between n-GaN material and Ni (25nm)/Au (25nm). The impact of surface treatments on GaN to Schottky contact are researched, and find that the hydrochloric acid:hydrofluoric acid:water (HCl:HF:H2O=1:1:10) method of surface treatment can obtained the best results (Ideal factor:3.17); the ICP treatment is the worst (Ideal factor:12.17). Two n-GaN Schottky diodes with different structure were made, and the voltage and current characteristics were analysised, showing that ICP etching can fabricate the ohmic contact more easily. The detector's schottky contact was made on mesa, and the ohmic contact was made in the channel (made by ICP etching). The schottky diode has ideal voltage and current characteristics. By the analysis of a radiation spectrum, we find that the device can detect the 241Am a particles, and the detection efficiency and resolution of the device can be influenced by the higher reverse leakage current, narrow depletion area, and low anti-bias.Therefore, improving the schottky contacts technics, reducing the reverse leakage current, widening the thickness of depletion area, enhancing the breakdown voltage, and using free-standing GaN materials to fabricate schottky and ohmic contacts at different surface are our next step to make a new radiation detector with higher detection efficiency and resolution.