Abstract: In this paper, optical methods are used to study the physical properties of large-area single-layer, few-layer and bulk WS₂ grown on sapphire substrates. Firstly, the atomic force microscope is used to estimate the number of layers of the samples, and the X-ray diffraction is used to judge their single-crystal properties. Then, through Raman spectra and photoluminescence spectra, the optical characteristics of the samples are studied. It is found that the E¹_2g mode and A_1g mode are obvious and sharp, indicating that the lattice structure is relatively complete, and the two modes shift in frequency as the number of layers increases. The direct exciton transition peaks of single-layer and multi-layer WS₂ are both asymmetric indicating that there is charge doping, and their photoluminescence intensity weakens as the number of layers increases. Further, by testing variable excitation power Raman spectra and variable excitation power photoluminescence spectra, it is found that the E¹_2g mode in few-layer and bulk WS₂ does not shift in frequency as the excitation power increases, indicating that the laser thermal effect can be ignored.- DOI:10.3969/j.issn.1000-1565.2024.06.006不同厚度WS₂光学性质吴春林¹,杨明明¹,谭丽¹,穆轩宇¹,郑洪¹,王佳乐¹,兰飞飞²,李晓莉¹(1.河北大学 物理科学与技术学院,河北 保定 071002;2.中国电子科技集团公司 第四十六研究所,天津 300220)摘 要:利用光学手段对蓝宝石衬底上生长的大面积单层、少层、块体WS₂的物理性质进行研究.首先利用原子力显微镜测量样品的厚度估算样品层数,并利用X线衍射测量样品的晶相判断其单晶特性.然后通过拉曼光谱和光致发光光谱技术研究样品的质量和光学特性,发现E¹_2g模和A_1g模明显且尖锐,说明晶格结构比较完整,2个模式随着层数增加发生频移;单层和多层WS₂的直接激子跃迁峰均存在不对称性,说明都存在电荷掺杂,其光致发光强度随着层数增加发生减弱.进一步通过测试变激发功率拉曼光谱和变激发功率光致发光光谱,发现少层、块体WS₂中的E¹_2g模随着激发功率的增加未发生频移,说明激光热效应可以忽略;少层、块体WS₂中的直接激子跃迁峰随激发功率的增加发生频移,说明存在载流子的相互作用;少层WS₂光致发光强度的变化幅度大于块体,这与层间相互作用强弱有关.关键词:WS₂;蓝宝石;化学气相沉积;拉曼光谱;光致发光光谱;变激发功率中图分类号:O433 文献标志码:A 文章编号:1000-1565(2024)06-0612-07Optical properties of WS₂ with different thicknessWU Chunlin¹,YANG Mingming¹,TAN Li¹,MU Xuanyu¹,ZHENG Hong¹,WANG Jiale¹,LAN Feifei²,LI Xiaoli¹(1. College of Physics Science and Technology, Hebei University, Baoding 071002, China;2. The 46th Research Institute of China Electronics Technology Group Corporation, Tianjin 300220, China)Abstract: In this paper, optical methods are used to study the physical properties of large-area single-layer, few-layer and bulk WS₂ grown on sapphire substrates. Firstly, the atomic force microscope is used to estimate the number of layers of the samples, and the X-ray diffraction is used to judge their single-crystal properties. Then, through Raman spectra and photoluminescence spectra, the optical characteristics of the samples are studied. It is found that the E¹_2g mode and A_1g mode are obvious and sharp, indicating that the lattice structure is relatively complete, and the two modes shift in frequency as the number of layers increases. The direct exciton transition peaks of single-layer and multi-layer WS₂ are both asymmetric indicating that there is charge doping, and their photoluminescence intensity weakens as the number of layers increases. Further, by testing variable excitation power Raman spectra and variable excitation power photoluminescence spectra, it is found that the E¹_2g mode in few-layer and bulk WS₂ does not shift in frequency as the excitation power increases, indicating that the laser thermal effect can be ignored.- 收稿日期:2023 -10-30;修回日期:2024-09-09 基金项目:河北省自然科学基金面上项目(A2024201029) 第一作者:吴春林(1997—),男,河北大学在读硕士研究生,主要从事半导体光学方向研究.E-mail:wuchunlin202406@126.com 通信作者:李晓莉(1982—),女,河北大学教授,博士,主要从事半导体光学方向研究.E-mail:xiaolili@hbu.edu.cn 第6期吴春林等:不同厚度WS₂光学性质河北大学学报(自然科学版) 第44卷The direct exciton transition peaks in few-layer and bulk WS₂ shift in frequency as the excitation power increases, indicating that there is carrier-carrier interaction. The variation of the photoluminescence intensity of few-layer WS₂ is larger than that of the bulk, which is related to the strength of the interlayer interaction.

Key words: WS₂, sapphire, chemical vapor deposition(CVD), Raman spectra, photoluminescence spectroscopy, variable excitation power