Preparation And Investigation Of ?-Ga₂O₃ And Homogeneous Pn Junction By Electric Field Assisted Chemical Vapor Deposition

Monoclinic?-Ga₂O₃ is an III-VI clan direct wide band gap semiconductor materials and wide band gap of 4.9 eV with excellent chemical and thermal stability.It is a promising candidate for high-temperature gas sensors,UV detectors and power electronics devices.Normally,undoped?-Ga₂O₃ material is intrinsically n-type conductivity,but p-type doping?-Ga₂O₃ is still a major obstacle.According to the present difficulties on synthesizing p-type?-Ga₂O₃ material and the crystalline quality of hetero-epitaxial grown?-Ga₂O₃ thin film is bad.In this paper,a?-Ga₂O₃ thin film was fabricated on a patterned sapphire substrates?PSS?using an external electric field assisted chemical vapor deposition?CVD?method.The influence of the applied voltage on the morphology,structure and optical properties of?-Ga₂O₃ was investigated.In addition,the Zn-doped?-Ga₂O₃/n-type?-Ga₂O₃ films homogeneous pn junction was fabricated,and its electrical properties were studied.The main research contents of the paper are as follows:?1?A uniform and regularly arranged?-Ga₂O₃ microstructures was grown on PSS substrate by external electric field assisted chemical vapor deposition method under different applied voltages.It has been found that the magnitude of the external electric voltage has a great influence on the growth rate,growth morphology and crystal quality of?-Ga₂O₃.When the external electric voltage is small,the crystal growth is slow and the crystal quality is poor.With the increase of the external electric voltage,the?-Ga₂O₃ growth on the PSS substrate is faster and the crystal quality is gradually getting better.When the external electric voltage is55V,?-Ga₂O₃ film structure with high crystalline quality was prepared.Furthermore,the absorption spectrum of?-Ga₂O₃ indicated that the absorption edge of the sample showed blue shift with the increase of the external electric voltage.We think that the crystal quality of the sample being improved after the external electric field.?2?The Zn-doped?-Ga₂O₃/n-type?-Ga₂O₃ films pn homojunction was successfully fabricated on the PSS by external electric field assisted CVD method under the external electric voltage 55V.The SEM were showed that the Zn-doped?-Ga₂O₃ and undoped?-Ga₂O₃ with smooth surface and thin film structures were prepared under the external electric voltage 55V.The XRD indicated that both Zn-doped?-Ga₂O₃ and undoped?-Ga₂O₃films have higher crystal quality.Moreover,Hall measurement indicated that the conductivity type was p-type,the carrier concentration was 9.23×10¹⁶/cm³,and the mobility was 3.21cm²V^-1s^-1.The current-voltage?I-V?characteristic of the homojunction device showed a good rectifying behavior of having a turn-on voltage of about 4.0 V.The above results show that we can prepare higher quality n-type and p-type?-Ga₂O₃ thin films by this simple and flexible external electric field assisted CVD method,which provided a method of material preparation for the development of?-Ga₂O₃ based optoelectronic devices.