Effect of Cd/As flux ratio and annealing process on the transport properties of Cd3As2 films grown by molecular beam epitaxy

Abstract

To study how the Cd/As flux ratio affects the microstructure and transport properties for Cd _3 As _2 films, we used molecular beam epitaxy (MBE) to grow Cd _3 As _2 (224) thin films on CdTe (111)/GaAs (001) virtual substrates. The effects of Cd/As flux ratio, during the grown process, on the electrical properties and surface morphology of the sample was studied. The films grown at lower Cd/As flux ratio have higher electron mobility and longer effective dephasing length. With decreasing Cd/As flux ratio, the magnetoresistance (MR) of the film changes from negative to positive. These results show that a lower beam ratio is beneficial to improve the crystal quality. In order to optimize the electrical properties of the films, the effect of annealing on the electron mobility and MR have been studied. After annealing, the MR changes from negative to positive, the electron mobility increase by 8 times, and the MR increase from 15% to 360% at 9 T. These results indicate that annealing is an effective method to optimize the electrical properties of Cd _3 As _2 epitaxial films.

Keywords

• Cd3As2
• MBE
• flux ratio
• annealing
• magnetoresistance