Preparation And Properties Of Si Doped Trench Schottky Photodiode

Ultraviolet(UV)photoelectric detection technology has a wide range of applications in civil and military fields,such as biological health,environmental monitoring,flame sensing,secure communication,space science and missile tracking,etc.In recent years,a variety of photodetectors based on wide bandgap semiconductors like Ga2O3,SiC,ZnO,AlGaN,MgZnO and diamond are developing rapidly.As a kind of direct bandgap semiconducting materials,β-Ga2O3 is highly praised because of its～4.9 eV bandgap.And β-Ga2O3 has the advantages of high optical absorption coefficient in the solar-blind region of the whole electromagnetic spectrum along with good chemical and thermal stability,which make it be an ideal semiconductor material for the preparation of solar-blind UV detectors.However,the poor conductivity of intrinsic βGa2O3 and the contacts between metals and β-Ga2O3 limit the performance of β-Ga2O3 devices,so researchers have carried out different important processes and found that Doping is an effective way to adjust the electrical and photoelectric properties,and proved that the optical and electrical properties of β-Ga2O3 are significantly improved by Si dopants.Meanwhile,with the development of device manufacturing technology,advanced structures including heterojunction,nanowire,field plate and trench have appeared,which further improve the performance of the device.Among them,the trench SBD structure is widely used because of the reduced surface field effect.Based on the above two methods of device optimizations,in this paper,Si-doped O-Ga2O3 thin films were deposited on sapphire substrate by MOCVD and Schottky diode solar-blind UV detector with trench anode structure was fabricated by BCl3/Ar plasma etching.The measurement of its photoelectric performances show that it has a promised prospect for its application of Ga203 Schottky diode photodetectors.The main research achievements are stated as follows:1.The Si doped β-Ga2O3 thin films were grown by MOCVD on(001)phase sapphire as substrate,and was measured by XRD,displays a single crystallinity along the(201),(402)and(603)directions,and the UV-Vis absorption spectrum is used to verify that the absorption in the solar blind UV region is stronger than that in other bands,shows an absorption edge at 218 nm.The bandgap width of the Si doped β-Ga2O3 film is 4.98 eV.2.The transverse Schottky diode with trench anode structure is designed and prepared on silicon doped β-Ga2O3 film by photolithography and ICP etching.The trench depth is about 60nm.Ni/Au and Ti/Au are used as the metal electrode materials of the Schottky diode respectively,and the electrode size is 0.8 × 0.8 mm2 with spacing of 8 μm.3.The performance of the solar blind photoelectric sensor prepared by silicon doped β-Ga2O3 grooved Schottky diode is investigated.The results show that This photodiode works as a dual-mode solar-blind ultraviolet sensor.Schottky photodiodes could create built-in potential in the depletion layer,which effectively separates charge carriers.In the forward biases,the current transport mechanism is like a photoconductor,i.e.operation in a photoconductive mode;while in reverse biases,its electrical behavior is governed by thermionic electron emission theory,translating to a depletion mode operation.This photodiode works as a dualmode solar-blind ultraviolet sensor with a PDCR of 3.93×105,a Responsivity of 152.63 A/W,an EQE of 74653%,rise and decay time of 0.06 s and 0.06 s,under the irradiation of 254 nm ultraviolet light with intensity of 200 μW·cm-2.Moreover,it has the potential to be a selfpowered photodetector at zero bias.In general,this trench Schottky contact design has a good developing prospect in the field of ultraviolet solar-blind detection with high performances.