Study Of Ohmic Contact And MSM UV Detector Based On GaN

This work was supported by The State Science and Technology Ministry of P.R.China under the contact No.G20000683-06, and by the National Natural Science Foundation of P.R.China under grant No.60046001.Gallium Nitride is one of the 3rd generation semiconductor materials. From 1990's, GaN has attracted more and more attention and advanced rapidly, mainly due to its direct transition, wide band gap (~3.4eV) and other excellent characters. At the same time, the rapid progress on devices requires better ohmic contact between metals and GaN, for example, the short-wave LD requires specific contact resistivity lower than 10-4Ωcm2.In this paper, we presented a comprehensive review of the research history and current status of GaN material and the devices based on GaN. We've focused on improving the GaN-metal ohmic contact characters and achieved some encouraging results. In addition, We've finished some researched work on MSM UV detector.The main work includes four contents as follow:1) The electrodes annealed in various temperatures were studied. With X-ray diffraction spectroscopy (XRD) and SIMS, the interfacial reaction is analyzed and a new two-step annealing method is suggested.2) The effects of surface treatment on non-alloyed Ti/Al ohmic contacts to n-type GaN were investigated. A specific contact resistivity of 4.85-5.65X10-4 Ω cm2 for the Ti/Al non-alloyed ohmic contact to n-type GaN which is treated with CH3CSNH2 has been obtained, and the PL performance of the sample was also improved.3) MSM UV detector based on both GaN/Si and GaN/Al2O3 were fabricated.4) Simulated the electric field in MSM structure, and the effects of MSM structure geometry parameters on electric field were analyzed.