Controlled growth of Mn1-xZnxFe2O4 ferrite films and opto-electromagnetic properties of two-dimensional graphene/ferrite heterojunction devices

Spinel ferrite thin films have attracted the attention of a new generation of opto-electromagnetic multifunctional integrated devices due to their excellent magnetic semiconductor properties and tunable wide bandgap. In this paper, a novel [graphene/Mn 1-x Zn x Fe 2 O 4 /SiO 2 /p-Si] heterojunction field-effect transistor (x=0.45—0.65) is designed, an n-type spinel Mn 1-x Zn x Fe 2 O 4 (MnZn) magnetic semiconductor film is grown on a SiO 2 /p-Si substrate, and the saturation magnetization and conductivity of the ferrite film are controlled by doping amount x and annealing temperature, and then a monolayer of graphene film is transplanted on its surface through a wet transfer process. The experimental results show that the negative gate voltage exerts a significant modulation effect on both the source-drain current and the photocurrent in the device. This is mainly due to the change in the probability of interband electronic transitions in the graphene film due to the magnetic moment distribution of the MnZn film, resulting in an abrupt change in the drain resistance. The infrared optoelectronic performance test further verified the migration and transformation mechanisms of electrons and photoelectrons under electrical, magnetic and optical fields in graphene/MnZn heterojunction. In addition, terahertz phase shift testing proves that the valence and conduction bands of graphene form multiple secondary energy levels, which can regulate the band gap of the heterojunction. These results will pave the way for field-effect transistors to be modulated not only in optical fields, but also as multifunctional devices in electric and magnetic fields.