Contact Of Semiconducting Gallium Oxide With Metals

Monoclinic gallium oxide is large direct band-gap oxide semiconductor material,and its band-gap is about 4.8~4.9 eV, which correspond to the deep ultraviolet light. t is very suitable for the production of deep ultraviolet optical devices. In addition, its Baliga merit factor(εμEb3) is the second only to diamond in theory. Gallium oxide will be an important candidate for the development of power semiconductor devices.Since metal-semiconductor contact feature is a base of the semiconductor devices research.For this, this thesis would be around the central task of gallium oxide semiconductor device processing. First of all, the metal-semiconductor contact features of gallium oxide were studied. And the technology method of Ohmic contact was explored. And future homoepitaxial thin films on the single crystal gallium oxide substrate were for the material basis. The photoconductive detector with ohmic contact characteristics and Schottky diode with Schottky contact characteristics were prepared. The properties of gallium oxide and metal contact control methods were verified in the application of devices.Because the price of gallium oxide single crystal is expensive and the sources of supply were limited, Sn doped gallium oxide thin films were prepared on sapphire substrates to research the characteristics of gallium oxide and metal contact in this paper. For this, Sn-doped gallium oxide films were grown on sapphire substrates by molecular beam epitaxy in the paper firstly. The microstructure of thin films with different doping concentrations were studied. The Ti/Au electrodes were prepared by electron beam evaporation. Then the heat treatment processing parameters of annealing temperature and annealing time were studied carefully about the properties of gallium oxide films contact with different Sn-doped concentrations. It was found that electrodes were annealed 30 s at 850 ℃ N2 atmosphere and the lowest contact resistance 5.82×10-2 Ω·cm2. The basis technical methods of Ohmic contact characteristics were explored for device development foundation.Finally, the photoconductive ultraviolet detectors with Ohmic contact characteristics and the Schottky diodes with Schottky contact characteristics were developed on the homoepitaxial gallium oxide thin films, which were prepared on gallium oxide single crystal substrates. For the photoconductive ultraviolet detectors,the peak value of spectral response curve appeared at about 245 nm, and maximum optical responsivity and optical responsivity under 280 nm ratio reached two orders of magnitude, which indicated that the device has excellent response characteristics at blind ultraviolet area. For the Schottky diode, the value of forward threshold voltage was about 1 V. The value of the ideality factor was 38.6. The device showed the typical characteristics of a Schottky junction rectifier.