| The development of power electronic technology is closely related to the progress of power devices.The emergence of new power devices and power integrated circuits has greatly improved the efficiency and power density of power electronic circuits.Power diodes as basic power devices are widely used in rectifier and DC-DC converter.Along with power electronic system towards high-integration,high-power and high frequency,it's difficult for the traditional high voltage resistant PN junction diode to competent the ever-renewing power electronics.Wide bandgap semiconductor materials provide a new development opportunity for power electronic technology.The Schottky barrier diodes based on wide bandgap semiconductor materials always can withstand high voltage and work under high frequency that can satisfy the current needs very well.Gallium oxide?Ga2O3?has been attracted increased attention as an emerging wide bandgap semiconductor material in recent years.Ga2O3 is well suited for Schottky diode for its ultra-wide bandgap?4.9 eV?,high breakdown electric fields?-8 MV/cm?,n-type doping concentration can be controlled in the wide range of 1015?1019 cm-3 and low cost single crystal growth technology.In recent years,there have been many studies on Ga2O3 Schottky barrier diodes and MOSFET because of the availability of economical device-quality native substrates that fully demonstrates its great potential for power devices.Since the study of Ga2O3 is still in its infancy,important issues such as how-to growth larger-size,high-quality single crystal substrate,research unknown physical properties,characterize the defects of single crystal and the interface state of devices and improve the devices preparation process are still required to be explored and resolved.This paper mainly focuses on Ga2O3 power Schottky barrier diodes,a series of innovative research results have been achieved as follow:1.Explore the process steps of device preparation and fabricate Ga2O3 Schottky barrier diodes:Improving the fabrication process of Ga2O3 Schottky barrier diodes which mainly include improvement of optical lithography process condition,optimal etching process conditions and optimize ohmic contact for low contact resistance by used PECVD annealing.It was found that the device performance was significantly improved by increasing the doping concentration of Ga2O3 substrate and combining the optimized condition of technology.2.The basic physical and temperature dependent properties of Ga2O3 Schottky barrier diodes were verified by experiments:The basic current voltage characteristics and capacitance voltage characteristics are analyzed by data fitting to reflect the device performance.The image force on the interface and the inhomogeneity of barrier height are studied by the analysis of temperature dependent current voltage characteristics and capacitance voltage characteristics which are obtained from variable temperature test results.The data fitting results of the relationship between the ideal factor and the barrier height with temperature shows that the Gaussian distribution of the barrier height.3.Research on the high frequency rectification characteristics of Ga2O3 Schottky barrier diode:The reverse recovery time of the device is tested to reflect the switching capability of the device.In order to investigate the rectification characteristics of power Schottky diode,the function of rectifying circuits had been analyzed by simulation and experiment results.The circuit was built and optimized by referred to simulation results.And then,in order to characterize the high frequency rectification capability of Schottky diodes,an oscilloscope is used to observe the output waveform of Ga2O3 Schottky barrier diode at different frequencies of AC signal.In the end,the improvement direction of high frequency application of Ga2O3 Schottky barrier diode was analyzed. |
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