基于XPS与XAS的稀磁半导体GaMnN电子结构研究

Study on electronic structure of dilute magnetic semiconductor GaMnN based on XPS and XAS

采用基于同步辐射技术的X射线光电子能谱(XPS)与X射线吸收谱(XAS)测试由金属有机化学气相沉积(MOCVD)技术制备的不同Mn掺杂浓度的稀磁半导体GaMnN薄膜的电子结构,探究Mn掺杂浓度对磁性原子Mn周围的局域环境和电子态等方面的影响,并阐述材料铁磁性变化的机理.XPS和XAS图谱分析表明:Mn^(2+)和Mn^(3+)共存于薄膜样品内,样品D中Mn^(2+)占比高达70%-80%,N空位随Mn掺杂浓度增加而增多且N空位能够使空穴浓度降低,导致Mn 3 d和N 2p轨道间的相互交换作用减小,从而减弱体系铁磁性.此外,Mn不同的掺杂浓度会影响GaMnN薄膜p-d耦合杂化能力的强弱,当掺Mn 1.8%时具有较强的p-d耦合杂化能力.

This paper is based on the X-ray photoelectron spectroscopy(XPS)and X-ray absorption spectroscopy(XAS)with the synchrotron radiation technology.It aims to test the electronic structures of dilute magnetic semiconductor GaMnN films with different Mn doping concentrations prepared by metal organic chemical vapor deposition technology(MOCVD),to explore the influences of Mn doping concentration on the local environment and electronic states of the magnetic atom Mn,and hence to expose the mechanism for the change of material ferromagnetism.The XPS and XAS data analysis show that Mn^(2+) and Mn^(3+) coexist in the film samples,the proportion of Mn^(2+) in sample D is as high as 70%-80%;the N vacancy increases with the increase of Mn doping concentration and it can reduce the hole concentration,as a result,the exchange interaction between Mn 3 d and N 2 p orbitals is reduced,which weakens the ferromagnetism of the system.In addition,Mn doping concentration also affects the strength of the p-d coupling hybridization ability of GaMnN films.When the Mn doping concentration is 0.018,the system has a strong p-d coupling hybridization ability.