Research On Preparation And Properties Of High Spin Hall Angle Semiconductor And Alloy Films

Moore's law is gradually invalid,and the development of semiconductor technology in traditional CMOS process is close to the physical limit.With the shortening of device size,the quantum effect and heating problems of devices are becoming more and more serious,and the development of traditional semiconductor has entered a bottleneck period.In order to solve this problem,a new generation of electronic information devices based on electron spin came into being.Electron spin devices have many advantages,such as low power consumption,easy integration and so on.Therefore,the research and development of a new generation of spintronic materials and devices has become one of the possible directions to break through the development of semiconductor technology.This paper mainly focuses on three problems of spin electron technology and makes a little bit progress:spin current high injection semiconductor,inverse spin Hall effect mechanism of laser modulation and searching for new alloy materials with higher spin Hall angle.Through ferromagnetic resonance measurement,the Gilbert damping,spin mixed conductance and saturation magnetization of YIG(200 nm)/Ge,YIG(200 nm)/Ge Sn,YIG(200 nm)/Ta W₃ and YIG(200 nm)/Pt₈Gd₂ heterostructures are studied.The experiment estimates of spin diffusion length and spin Hall angle are obtained.Firstly,the theory of our work is collected from the work of former people:two precession models of magnetic moment are derived from the origin of magnetism and magnetic energy,and then the related theories of ferromagnetic resonance,spin pump effect,spin Hall effect,inverse spin Hall effect and their theoretical mechanisms are described in detail.Secondly,the sample preparation technology and testing technology are briefly introduced.Then,through the study of ferromagnetic resonance and laser modulated inverse spin Hall effect in YIG(200 nm)/Ge system,we realized the large spin injection of semiconductor and explained the main mechanism of laser modulated inverse spin Hall signal.The large spin injection in semiconductors is mainly reflected in the large spin mixed conductance.YIG(200 nm)/Ge(60 nm)and YIG(200 nm)/Ge Sn(60 nm)are obtained experimentally and the spin mixing conductance is 5.4×10¹⁸ m^-2 and 7.2×10¹⁸m^-2 respectively;The laser power modulation mechanism of inverse spin Hall voltage is completed by using infrared laser to modulate the spin pump effect.The experimental results show that:by enhancing the power of the infrared laser,the saturation magnetization of YIG film is significantly reduced;the thermal gradient caused by laser will produce spin injection of spin Seebeck effect,which is compensated by the decrease of spin pump effect due to the decrease of saturation magnetization,so the voltage signal detected finally reaches saturation.Finally,in order to find the high spin Hall angle alloy materials,we used the insulating ferromagnetic YIG single crystal film as the magnetic layer,and prepared new types of Ta W₃ and Pt₈Gd₂ alloy materials by magnetron sputtering.The spin pumping effect and inverse spin Hall effect of YIG(200 nm)/Ta W₃ and YIG(200 nm)/Pt₈Gd₂heterojunction were studied.The results show that the spin Hall angle of Pt₈Gd₂ alloy is0.501 and the spin Hall angle of Ta W₃ alloy is-0.0587.The new spin Hall alloy material developed by us will help to reduce the current density of the reversal magnetic moment of SOT,and the alloy can be applied to the next generation of SOT-MRAM with high density,low power consumption and non-volatile.