耦合p-n结室温低场大磁阻机理研究

Recently the large magnetoresistance effect discovered in nonmagnetic semiconductors offers an alternative route to renew magnetoelectronics without ferromagnets. However, it is still a great challenge to retain such large magnetoresistance at room temperature and low magnetic field. The aim in this project is to realize magnetic-field-manipulated p-n junctions coupling in order to achieve the larger magnetoresistance under the lower magnetic field at room temperature. Analogous to electric amplification in the transistor, we propose a magnetoresistance amplification effect in coupled p-n junctions, where the device current is significantly controlled by magnetic-field-manipulated coupling of p-n junctions. Firstly, we plan to fabricate the coupled p-n junction device by adjusting the doped atom compositions, concentrations and distributions. The fabrication methods are based on the ion diffusion or ion implantation combined with the sputtering technology. Secondly, we plan to measure the electrical transport properties at various temperatures, and systematically analyze the temperature-dependent coupling of p-n junctions owing to the change of the carrier diffusion length. Thirdly, for the coupled p-n junctions devices we plan to study their magnetic field-induced transport behaviors by varying the external magnetic field amplitudes and orientations, and further measure the magnetoresistance and the magnetic amplification effect. Finally, combined with the simulation results for the coupled p-n junctions under electric field and magnetic field, we could analyze the mechanism of the magnetic field-induced magnetoresistance amplification behaviors in details. The study will not only obtain the semiconductor magnetic sensor with both larger magnetoresistance and higher temperature, but also give a new insight into the future magneto-electronics.

最近非磁性材料大磁阻的发现（室温磁阻>2000%）为磁电子学发展提供了新的方向，但实现大磁阻仍需要高的工作磁场和低的测量温度。本项目以研究p-n结耦合后的磁阻放大机理为目的，以降低磁场和提高器件温度为关键，以p-n结耦合对磁阻的放大为手段，来实现室温、低场、大磁阻p-n结耦合器件。拟用离子注入技术制备具有不同耦合强度的p-n结器件，结合结构观测和电性测量（电阻和霍尔)，掌握不同掺杂离子浓度，迁移率和空间电荷区分布的制备工艺。通过施加磁场和改变温度，调节迁移率和空间电荷区形状，来实现p-n结耦合的调控。在此基础上，系统改变磁场大小和取向，获得具有不同耦合强度p-n结器件的磁阻放大特性和温度调制规律，并结合电磁场分布模拟计算，进一步理解p-n结耦合磁阻放大机理。该研究不仅可以获得更高温度、更低磁场和更大磁电阻率的磁控p-n结半导体器件，而且为磁电子器件的设计和应用提供新思路。

本项目利用p-n结耦合来提高p-n结器件对磁场响应的灵敏度和幅值，通过离子注入，获得了具有不同耦合强度的p-n结器件的关键技术；结合结构观测和电性测量（电阻和霍尔)，掌握不同掺杂离子浓度，迁移率和空间电荷区分布对p-n结耦合调控的影响，获得具有不同耦合强度p-n结器件的磁阻放大特性和温度调制规律，实现了室温、低场、大磁阻p-n结耦合器件。再结合电磁场分布模拟计算，我们总结了p-n结耦合磁阻放大机理。该研究不仅获得了更高温度、更低磁场和更大磁电阻率的磁控p-n结半导体器件，而且为磁电子器件的设计和应用提供新思路。目前在项目资助下发表已标注SCI论文17篇，其中以本人为第一（或通讯）作者发表论文8篇，授权发明专利2项。期间培养本科毕业生4名，毕业硕士研究生2名，在读研究生6名，参加2018-2021历年国内秋季会议，2018年第二届半导体青年学术会议并作邀请报告，2021年第十六届磁学理论会议，和在美国华盛顿举办的2019InterMag&MMM联合会议。