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Development Of Gallium Oxide Schottky Barrier Diodes

Posted on:2019-06-22Degree:MasterType:Thesis
Country:ChinaCandidate:X Y XingFull Text:PDF
GTID:2428330572950233Subject:Microelectronics and Solid State Electronics
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Gallium oxide?Ga2O3?has obvious advantages compared to third generation semiconductor materials such as SiC and GaN due to its wide band gap,high breakdown field strength,stable physicochemical property,and other superior characteristics.Schottky barrier diodes?SBDs?fabricated with Ga2O3 can theoretically achieve desirable electrical characteristics,and are expected to make breakthrough in power device research.This article studies Ga2O3 Schottky diodes from both simulation and experimental aspects.The results obtained are shown as follow:First,the working principle and device characteristics of Ga2O3 SBD are described.The physical model that can affect the device is introduced in combination with the parameters of Ga2O3.This provides a theoretical basis for the following study.Second,the Ga2O3 Schottky diode is simulated with Silvaco Atlas device simulation software,and the data including reverse breakdown voltage which is 357V is obtained.Based on this,the floating metal ring?FMR?structure is added,and the structural parameters such as space,width and number of metal rings are optimized to obtain better breakdown characteristics.The electric field distribution diagram of the device shows that the metal ring expands the depletion region in the horizontal direction,alleviating the phenomenon that the electric field lines concentrate at the edge of the Schottky junction.This is the reason why the floating metal ring structure can improve the reverse characteristic.Through simulation and comparison,the optimal structure is obtained which contains three metal rings and the space of the first ring and the anode is 2?m,and the breakdown voltage is 965V.Third,the material research shows that increasing Al composition in Ga2O3 to form?AlGa?2O3 material can increase the band gap and high pressure resistance of the device.We prepared vertical structure Schottky diodes with?AlGa?2O3.Prior to tape-out,we performed XRD,XPS,and other tests on the material.The results confirmed the realization of epitaxial?AlGa?2O3 on a Ga2O3 substrate,and the Al composition in the material was measured to be 19.30%.After preparing the device we conducted a number of electrical tests.The forward characteristic of the I-V test shows that the device has a turn-on voltage of 0.5V.The ideal factor calculated from the characteristic curve is 1.96.The breakdown voltage of the device obtained from the reverse I-V test is 143V.The barrier height is 1.16eV through the C-V test and related calculations.In addition,we investigate the effect of temperature on the forward characteristic of the SBD and extract the ideal factors of the device at different temperatures.The result suggests that the ideal factor increases first and then decreases with increasing temperature.This shows that the actual forward current of the device is affected by a variety of mechanisms.Changes in temperature will affect the composite current and other mechanisms.We have studied the relationship between different growth temperature of material and the reverse characteristic of the device.It was found that the higher the growth temperature,the higher the breakdown voltage of a device fabricated with this material.According to the results of relevant research,the increase of the material growth temperature will further increase the width of the band gap,and the increase of the band gap is related to the increase of the breakdown voltage.Fourth,we have applied the simulation experience and conclusion to the process experiment to prepare Ga2O3 SBDs with a floating metal ring.We designed the layout of the metal ring with different structural parameters to explore its influence on the reverse characteristic.After the tape-out experiment,we conducted an I-V test on the Schottky diodes,paying particular attention to the reverse performance.The test results show that the breakdown voltage of the Schottky diode is 80.5V when there is no metal ring,and the voltage resistance of the device improves after adding the metal ring.With the change of the space and width of the metal ring,the breakdown voltage of the device shows a trend similar to that in the simulation.The optimum design parameters are that the space between the metal ring and the anode is 3?m,and the width of the metal ring is 3?m.The breakdown voltage is 127V under this circumstance.Last,a planar Schottky barrier diode was fabricated on a tin doped homoepitaxial gallium oxide film and electrically tested.Through the I-V test,the turn-on voltage of the device is0.5V,and the ideal factor has been calculated.
Keywords/Search Tags:Ga2O3 Schottky barrier diodes, simulation, preparation process, floating metal ring, electrical properties
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