Study On The Interface Of Spin Injection End Of Spin Light Emitting Diodes

Spin Light-Emitting Diode(Spin-LED)is an important spin electronic device formed in the field of semiconductor spintronics research on spin injection,manipulation and detection carried out by spintronics combined with semiconductor materials.The study of Spin-LED involves the materials,structure,and rich physical phenomena of the spin injection terminal and the active region.At present,materials based on Ta/CoFeB/MgO in-plane and perpendicular magnetic anisotropy have been successfully prepared and used as spin injection terminals in spin light-emitting diodes.At present,Ta/CoFeB/MgO-based in-plane and perpendicular magnetic anisotropic materials have been successfully prepared and used as spin injection terminals in Spin-LED.However,the quality of the interface formed during the growth of the film,such as the CoFeB/MgO interface or the MgO/GaAs(active region)interface,may be very important to the spin and charge injection efficiency.Therefore,improving the interface layer at the spin injection terminal is an effective way to improve the spin injection efficiency.We will focus on the effect of the spin injection interface of the Spin-LED on the charge injection,and explore the different spin injection interface produced by the MgO tunnel barrier layer and the effect of the interface on the electrical transport properties.Combined with the 1D Poisson program,the effect of MgO barrier layer on the electrical transport performance is confirmed.The main contents of this paper are as follows:1.The MgO tunnel barrier layer was prepared by molecular beam epitaxy and magnetron sputtering,resulting in different spin injection terminal,and the prepared two samples were named“MBE”and“sputtering”,respectively.The two types of samples are studied by energy band simulation,forward bias and annealing treatment.The results show that the V_TH is equal to the bias voltage when the Schottky barrier is zero;annealing can reduce the threshold voltage of“sputtering”sample,but has little effect on the threshold voltage of“MBE”sample;the MgO/GaAs interface of“MBE”sample before and after annealing is crystalline,and the MgO/GaAs interface of“sputtering”sample has an amorphous layer about 0.4nm thin,which can be improved by annealing.2.The band structure diagram of CoFeB/MgO/GaAs-In GaAs quantum well at the spin injection terminal of Spin-LED is simulated and the effects of bias voltage,MgO barrier layer and its thickness on Schottky barrier are investigated.The results show that the Schottky barrier can be reduced when the bias voltage is applied to Spin-LED devices,and the Schottky barrier decreases gradually with the increase of bias voltage,and the Schottky barrier decreases with the increase of the thickness of MgO barrier layer when a thin MgO barrier layer is added to ferromagnetic layer and semiconductor material to reduce Schottky barrier to improve the spin injection efficiency of the device.Under the premise that the MgO barrier layer is several nanometers,the Schottky barrier decreases with the increase of the thickness of the MgO barrier layer.