金属有机化学气相沉积生长Zn_(1-x)Mn_xSe薄膜的发光和磁光性质

Photoluminescence and Magneto-optical Properties of the Zn_(1-x)Mn_xSe Thin Film Grown by Metal Organic Chemical Vapor Deposition

利用金属有机化学气相沉积(MOCVD)方法在GaAs衬底上生长了不同组分的Zn1-xMnxSe薄膜。X射线衍射和X射线摇摆曲线证明样品具有较好的结晶质量。在低温、强磁场下对样品的发光进行了研究,在带边附近观察到两个发光峰的相对强度随着磁场增强发生了变化。通过变温光谱探讨了这两个发光峰的来源,并被分别归因于自由激子跃迁和与Mn有关的束缚态激子跃迁。同时随着磁场的增强,ZnMnSe带隙发光红移是由于类S带和类P带电子与Mn离子的3d5电子的自旋交换作用。

Zn1- xMnxSe belongs to a class of materials called diluted magnetic semiconductors （DMS） where their cations in a non-magnetic compound were partially replaced by magnetic ions. Within the rapidly evolving field of semiconductor spintronics researchers try to make the spin injection come true. Several approaches for spin injection have been realized, one of them is from a diluted magnetic semiconductor to a ferromagnetic semiconductor layer in an external magnetic field. It is important to prepare the polarized layer and to study their properties, since Zn1-xMnxSe as a polarized layer is popular with many researchers. In recent years, the material growth technique of Zn1-xMnxSe has been improved greatly. However, fewer researches related to Zn1-xMnxSe epilayers grown by metal-organic chemical vapor deposition （MOCVD） are reported than those grown by molecular beam epitaxy（ MBE）, although is more suitable for large scale production. Zn1-xMnxSe thin films with different Mn compositions are grown by metal-organic chemical vapor deposition（MOCVD） on GaAs substrate. We use Tricarbonyl （methylcyclopentadienyl） manganese （TCMn） as Mn source, use dimethylzinc （DMZn） and hydrogen selenide （H2Se） as Zn source and Se source, respectively. The growth temperature is 480℃. The growth pressure is 104 Pa. The thickness of the samples are 150 nm measured by scanning electron microscope （SEM）. Good crystallinity of sample is evidenced by X-ray diffraction and rocking curve measurements. Magneto-optical properties of Zn0. 88Mn0.12Se thin films are investigated in magnetic fields up to 8 T. Two emission peaks near the band edge were observed. At the same time, a relative change of the emission intensity between two peaks is shown, we attribute the two peaks to the free exciton emission and Mn induced bound state excitonic emission respectively. Meanwhile, the band gap shows a red shift with increasing magnetic field due to the large spTd change interaction