The growth and characterization of rhenium-doped WS2 single crystals
The growth and characterization of rhenium-doped WS2 single crystals
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DOI：
10.1088/0953-8984/16/12/025
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发表时间：
2004-03
期刊：
影响因子：
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通讯作者：
P. Yen;Yen-Ru Huang;K. Tiong
中科院分区：
文献类型：
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作者：
P. Yen;Yen-Ru Huang;K. Tiong
使用溴作为传输剂，通过化学气相传输方法生长了掺铼 WS2 单晶。 X射线衍射图分析发现，掺杂晶体以三层菱面体（3R）和两层六方（2H）结构的混合多型体结晶，而未掺杂晶体为2H形式。 W 5p 核能级附近的 X 射线光电子能谱 (XPS) 表现出强烈的不对称线形特征，位于高能侧的弱肩归因于 WS2 中存在少量铼。室温下的霍尔系数测量表明样品本质上是 n 型的。材料的掺杂效应通过温度相关的电导率、室温光吸收和压电反射 (PzR) 测量来表征。随着掺杂浓度的增加，电阻率急剧下降，表明掺杂化合物中有更多的载流子可用于传导。掺杂样品的间接能隙随着掺杂浓度的增加而出现红移。由于少量Re的存在，直接带边激子跃迁能表现出轻微的红移，并且由于杂质散射，激子跃迁特征的展宽参数增加。
Single crystals of rhenium-doped WS2 have been grown by the chemical vapour transport method using bromine as a transporting agent. From x-ray diffraction pattern analysis, the doped crystals are found to crystallize in mixed polytypes of the three-layer rhombohedral (3R) and two-layer hexagonal (2H) structures while the undoped one is in the 2H form. The x-ray photoelectron spectra (XPS) in the vicinity of W 5p core-level regime exhibit strongly asymmetric line-shape character and the weak shoulder located at higher energy side is attributed to the presence of a small amount of rhenium in WS2. Hall coefficient measurements at room temperature indicate that the samples are n-type in nature. The doping effects of the materials are characterized by temperature-dependent conductivity, room temperature optical absorption and piezoreflectance (PzR) measurements. The drastic decrease in resistivity with increasing doping concentration suggests that more charge carriers are available for conduction in the doped compounds. The indirect energy gap for the doped samples shows red shifts on increasing the doping concentration. The direct band edge excitonic transition energies show a slight red shift due to the presence of a small amount of Re and the broadening parameter of the excitonic transition features increases due to impurity scattering.