| Gallium oxide(?-Ga2O3)is a new generation of ultra-wide band gap semiconductor with high breakdown field,excellent thermal and chemical stability.It has a wide application prospect in solar blind ultraviolet detection,high voltage and high power electronic devices,etc.However,it is difficult for?-Ga2O3 to achieve p-type doping,which limits the realization of bipolar devices with better performance.In this paper,we propose to use p-type nickel oxide(NiO)semiconductor and n-type?-Ga2O3 to construct heterojunction to break through the above limitations.(1)The p-type NiO semiconductor was prepared by magnetron sputtering.The influention of different process conditions(such as sputtering power,chamber atmosphere and gas pressure)on the structural,optical and electrical properties of NiO thin films were investigated.p-type NiO thin films with excellent properties were obtained by optimizing the process parameters,and the effect of annealing on the properties was further studied.(2)The p-type NiO thin films were deposited on?-Ga2O3with(100),(-201)and(010)orientations,respectively.The energy band structure was analyzed by X-ray photoelectron spectroscopy(XPS)and ultraviolet visible spectrophotometer,and the correlation between the energy band structure of NiO/?-Ga2O3 heterojunction and the crystal orientation of?-Ga2O3was studied.The experimental results show that the valence band offsets of NiO and?-Ga2O3with three different crystal orientations are 2.37e V?2.02e V and 2.57e V respectively,and the conduction band offsets are 1.42e V?1.17e V and 1.77e V,respectively.The energy band structure of the interface of NiO and Ga2O3 is dependent on the orientation of the substrate,which may be due to the anisotropy of the gallium oxide crystal,which makes the crystal structure and stoichiometric ratio of the nickel oxide film have great differences.(3)Ga2O3/NiO heterojunction diodes were fabricated on(-201)oriented Ga2O3.The electrical and photoelectric characteristics of the devices were measured and analyzed.The rectifier has a rectification ratio of 2.11×108 and an ideal factor of about 2.22.It has a photoelectric response under the illumination of 254 nm wavelength and a responsivity of 1.3m A/W under the reverse bias of-5 V.It also has a self-powered characteristic.In this paper,based on the lack of p-type doping Ga2O3 and the lack of effective pn junction devices,the pn heterojunction diodes were prepared by NiO This device shows the potential of application in power electronic devices and optoelectronic devices,which provides reference experience for further development of gallium oxide heterojunction devices. |
PDF Full Text Request