錳摻雜對II-VI族半導體二維單層量子材料之光學特性與自旋行為之影響

Abstract

本研究聚焦在探討過渡金屬離子錳(Mn2+)以不同濃度摻雜對二維 II–VI 族半導體材料之晶體結構、光學響應與自旋行為的影響。研究材料包括 MnxCd₁₋ₓSe(en)0.5 及MnxZn₁₋ₓSe(en)0.5 ，皆採用溶劑熱法合成，並以高解析穿透式電子顯微鏡(HRTEM)、能量色散光譜(EDS)、X 光繞射(XRD)、拉曼光譜、電子順磁共振(EPR)及 X 光磁圓二色性光譜(XMCD)等多重表徵技術，系統性分析摻雜濃度與環境參數，例如:氣氛、磁場與溫度，對於材料性質的影響。實驗結果顯示，錳離子可均勻摻雜至材料晶格中，導致晶格收縮與內部應變，並造成能帶結構與激子結合能之調變。在光譜響應方面，以圓偏振與線偏振拉曼分析探討聲子強度之角度依賴性，以結果來看，LO (longitudinal optical) 模態具有明顯的偏振選擇性與磁場響應性，顯示出材料中存在強烈的自旋–軌道耦合(Spin-orbital coupling)與自旋選擇性光躍遷。XMCD 進一步證實錳摻雜後材料在不同磁場下的自旋態調變與賽曼分裂現象，並觀察到鎘原子亦受錳自旋極化影響，呈現自旋漣漪效應。該成果對於理解過渡金屬摻雜對二維量子材料光學響應、自旋動力學與能階重構機制提供具體實驗依據，對於自旋電子學、磁光元件與低維度光電應用之設計策略提供重要參考。This study investigates the impact of varying Mn2+ doping concentrations on the crystal structure, optical response, and spin behavior of solvothermally synthesized 2D II-VI semiconductor materials, MnxCd₁₋ₓSe(en)0.5 and MnxZn₁₋ₓSe(en)0.5. Comprehensive characterization using techniques including HRTEM, EDS, XRD, Raman spectroscopy, EPR, and XMCD was performed to analyze the effects of doping and environmental parameters like magnetic field and temperature.Results show that Mn2+ ions uniformly incorporate into the host lattice, inducing lattice contraction, internal strain, and modulating band structure and exciton binding energy. Polarized Raman spectroscopy revealed that the LO (longitudinal optical) phonon mode exhibits significant polarization selectivity and magnetic field response, indicating strong spin-orbit coupling and spin-selective optical transitions. XMCD studies further confirmed Mn-induced spin state modulation and Zeeman splitting under applied magnetic fields, and notably, a spin-ripple effect on neighboring Cd atoms due to Mn spin polarization.These findings provide crucial experimental evidence on how transition metal doping impacts the optical response, spin dynamics, and energy level reconstruction in 2D quantum materials. This work offers valuable insights for designing future spintronic, magneto-optical, and low-dimensional optoelectronic devices.