Transport Properties Controlled By Spin-Orbit Coupling In Semiconductor Heterostructures

Spintronics is a interdiscipline of magnetism and microelectronics. It seeks to use electron spin (spin up or spin down) to substitute the traditional charge-based electronics in order to design and develop a new generation Electronic products. Based on spins degree-of-freedom the investigation on the influence of spin-orbit coupling in electron transport has received much attention in recent years. The mesoscopic Semiconductor Heterostructures is an important part of nanometer circuit, Therefore, research on transport property of semiconductor quantum wire concerning spin-orbit coupling is a practical problem which has both commercial and academic applications.The spin injection in semiconductor plays a decisive role in realizing the spintronics devices. Related problem also bottleneck become the obstacles of its further applications. Thus it remains a challenge to find efficient ways and methods to obtain high spin-injection rate.In this thesis, using quantum-mechanics method as a theoretical background, combined with Landauer conductance formula and spin injection efficiency formula, we studied the transport properties in quasi-1D semiconductor Heterostructures with the present of Rashba spin-orbit coupling which sterms from the inversion asymmetry of the limited contact surface.Considering the spin polarization in metallic ferromagnet, the interfacial scattering, the band mismatch and different Rashba spin-orbit couplings in two quantum wires, we studied the conductance and spin injection within the framework of quantum mechanics in the Ferromagnet/Semiconductor1/Semiconductor 2 structure (an electric field along the y-axis in the positive direction in wire one, while there is no field in the area of quantum wire 2)and the ferromagnet/semiconductor 1 / semiconductor 2 / semiconductor 3 structure (an electric field along the y-axis in the positive direction in wire one, while there is an electric field along the z-axis in the positive direction in the area of quantum wire 2).Under the situation of the single-band effective mass approximation without the spin-orbit coupling induced intersubband mixing, respectively in system of FM/SC1/SC2 and the FM/SC1/SC2/SC3, we discussed the influence of the Rashba spin-orbit coupling intensity, the length of semiconductor quantity wire, and potential barrier in the ferromagnet /semiconductor and the semiconductor/semiconductor heterojunction to system's Transport Properties such as the conductance and spin injection efficiency.The results show that the conductance of two heterogeneous structure and the spin injection efficiency, change sensitively with the Rashba spin-orbit coupling strength, and with increasing Rashba oscillation wave vector the more obvious; the length of the semiconductor quantum wire greatly influence system conductance and the spin injection efficiency; Simultaneously we discovered that any potential barrier would hinder electronic the movement, and its quantity the degree is high related to that of spin mismatching at contact surface .We conclude that given an appropriate quantum wire length and Schottky barrier at the interface of heterogeneous materials, through the controlling of the external electric field or external voltage spin-orbit coupling strength, we can be obtained higher spin injection efficiency.