Epitaxial growth and magnetic polaron of ZnTe/Zn1-xMnxSe quantum dots with different Mn concentration

• Main Authors: Hsieh, Cheng-Hsuan, 謝承軒
• Other Authors: Chou, Wu-Ching
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/05179704803072877799

碩士 === 國立交通大學 === 電子物理系所 === 104 === Type II ZnTe/Zn1-xMnxSe quantum dots (QDs) with different ZnTe coverages from 2.0 to 4.0 monolayers (MLs) were grown by molecular beam epitaxy system. When the coverages of ZnTe QDs were less than 3.0 MLs, two peaks in the photoluminescence (PL) spectra were observed. The higher energy peak was attributed to the emission from the ZnTe wetting layer, and the lower energy peak was due to the emission from the QDs. The formation of ZnTe QDs was confirmed by the surface topography study of atomic force microscope (AFM). A series of ZnTe/Zn1-xMnxSe QDs with different Mn concentration were grown to study the influence of Mn concentration on the formation of magnetic polaron. The type II ZnTe/Zn1-xMnxSe QDs confine holes inside non-magnetic ZnTe QDs and the electrons situate outside the QDs and spin polarize Mn ions, which lead to the formation of magnetic polaron. The time-resolved PL shows the decreasing formation time of magnetic polaron from 96.2 ns to 8.4 ns as the Mn concentration increasing from 2.8% to 7.2%. Accordingly, the emission peak shift caused by the formation of magnetic polaron increases from 9.0 meV to 36.4 meV. Current study illustrates that the formation dynamics of magnetic polaron could be manipulated by the control of Mn concentration.