Growth And Properties Of ?AlGa?₂O₃ Epitaxial Thin Film And N-Doped Gallium Oxide

Gallium oxide,as a new type of wide bandgap semiconductor materials,has an excellent properties because of its wind bandgap and the large breakdown electric field.Through incorporating the aluminum to from the?AlGa?₂O₃ could modulate the bandgap and make it become winder,leading to the enhanced breakdown voltage.In this paper,?AlGa?₂O₃and n-doped Gallium oxide were grown on sapphire substrate by PLD.The influence of temperature and oxygen pressure on the properties of the thin films were systematically investigated as well as the application of research in the photodetectors.The results obtained are shown as follow:First,we discussed the influence of growth temperature and the oxygen pressure to the thin films through chossing the gallium oxide target material with 12%atomic ratio aluminum.The XRD results show that the?AlGa?₂O₃ thin films grown on sapphire substrate the preference orientation of?201?and shift towards the higher angle comparied with the Ga₂O₃ ones.The alteration of the oxygen pressure and growth temperature could change the Al composition in the(Al_0.12Ga_0.88)₂O₃ thin film in order to achieve the control of the bandgap.The growth temperature increases so as to the widen of the bandgap as the Al content increase in the?AlGa?₂O₃ thin films.The increase of the oxygen pressure also lead to the Al content decrease.Second,the?AlGa?₂O₃ thin film had the different Al composition with the change of oxygen pressure.We could increase the oxygen pressure to get the(Al_0.12Ga_0.88)₂O₃ thin film with lower Al content which could had the more excellent behave of the photocurrent and responsivity in photodectors comparied with the Ga₂O₃ ones.The lower Al content devices had the enhanced conductivity of the materials due to the shallow impurity-like defects,and the higher Al content devices had the degradation of photocurrent and pronounced persistent photoconductivity because of the large number of deep defects in the devices.Third,we discussed the performance of the Ga₂O₃ thin films with two-dimensional doped while using the silicon as the dopant.The XRD results show that,compared with the Ga₂O₃ XRD peaks,the Ga₂O₃ thin films with two-dimensional doped increases the XRD peak of the sample.The AFM results show that the surface of the thin films become rough while increasing the growth temperature and the mode of growth is Volmer-Weber.Equally,the optical absorption edge slope gently and shift towards low wavelength direction with the increase of growth temperature.Fourth,the properties of photodectors are associated with the growth temperature when the Ga₂O₃ thin film had the silicon as two-dementional doping dopant.The photodectors had higher photocurrent when the growth temperature raised to 750 degree.In the condition of the sample grown on 750 degree,the bias voltage is 20V and the density of light power is600?W/cm²,the ratio of photocurrent to dark current is more than 200.Time-dependent photocurrent characteristics of the photodectors show that the sample in growth temperature in 750 degree had a shorter decay process and enhanced photocurrent reached to 7000nA.