金刚石与磨料磨具工程2026，Vol.46Issue(4)：470-479,10.DOI:10.13394/j.cnki.jgszz.2025.0081
W,Ta掺杂过渡层的制备及其对 MPCVD单晶金刚石外延层质量的影响
Fabrication of W-and Ta-doped transition layers and their effects on qualities of MPCVD single crystal diamond epitaxial layers
摘要
Abstract
Objectives:Single crystal diamond is renowned as the"ultimate semiconductor material"and a"strategic advanced semiconductor material"due to its exceptional properties,including exceptional hardness,broad-spectrum optical transparency,wide bandgap,high thermal conductivity,high charge carrier mobility,and outstanding chemical and physical stability.These attributes make it highly suitable for a wide range of applications such as precision machining,optical windows,heat spreaders,semiconductor devices,and quantum information technologies.Nevertheless,the presence of various intrinsic defects in single crystal diamond significantly hampers its broader adoption in semiconductor applications.In particular,high-density threading dislocations are a major cause of performance degradation in diamond-based devices.Therefore,preparing high-quality,low-dislocation-density single crystal diamond is of critical importance for advancing its semiconductor applications.Methods:In this study,tungsten(W)-and tantalum(Ta)-doped interlayers are deposited on single crystal diamond seeds via hot filament chemical vapor deposition(HFCVD),with the growth behavior of these interlayers investigated under different filament currents.Subsequently,single crystal diamond is epitaxially grown on the seeds with doped interlayers using microwave plasma chemical vapor deposition(MPCVD).The effects of different doped interlayers on the dislocation density and infrared transmittance of the epitaxial diamond layers are systematically compared.The surface morphologies and crystalline qualities of both the doped interlayers and the MPCVD grown epitaxial layers are characterized using metallurgical microscopy and laser Raman spectroscopy.The chemical bonding states of elements within the interlayers are analyzed by X-ray photoelectron spectroscopy(XPS).The dislocation density and infrared transmittance of the MPCVD epitaxial layers are evaluated using X-ray diffraction rocking curve measurements and Fourier-transform infrared spectroscopy,respectively.Results:The results indicate that as the filament currents for W and Ta increase,both the crystalline quality and growth rates of the interlayers first improved and then deteriorated.At low currents,insufficient hydrogen atom etching leads to significant secondary nucleation on the surface of the doped diamond interlayers,resulting in poor quality.At high currents,severe graphitization occurs,considerably degrading the growth quality.When the filament currents for W and Ta are set to 30 A and 36 A,respectively,the resulting doped interlayers exhibit relatively high quality after 1.5 h of growth,with full width at half maximum(FWHM)values of the diamond Raman peak measuring 4.71 cm-1 and 5.49 cm-1,though slight surface polycrystallization is observed.XPS analysis confirms bonding interactions between W/Ta atoms and carbon atoms,which also cause the single crystal diamond to turn black.To suppress surface polycrystallization and minimize interfacial misfit dislocations during subsequent MPCVD epitaxial growth,the growth time is reduced,yielding smooth,nearly polycrystalline-free 5.0-µm-thick W-and Ta-doped interlayers with diamond Raman FWHM values of 4.60 cm-1 and 5.02 cm-1,respectively.After 50 h of MPCVD epitaxial growth,the W-doped interlayer reduces the dislocation density of the epitaxial layer by half an order of magnitude and achieves an infrared transmittance of 61%.In contrast,the Ta-doped interlayer performs poorly,yielding an optical transmittance of only 54%in the corresponding epitaxial layer.Conclusions:(1)With increasing W and Ta filament currents,the crystalline qualities of the diamond interlayers initially improve and then decline.Low-current growth results in increasing surface roughness and amorphous carbon impurities,while high currents cause severe graphitization.The optimal interlayer quality is achieved at 30 A for W and 36 A for Ta,with the W-doped interlayer exhibiting superior properties.(2)Reducing the growth time at these currents effectively suppresses surface polycrystallization and improves surface quality.XPS results further confirm substantial bonding between W/Ta atoms and carbon atoms in the diamond structure.(3)Compared to the Ta-doped interlayer,the 5.0-µm-thick W-doped interlayer significantly enhances the quality of the MPCVD-grown single crystal diamond epitaxial layer.The epitaxial layer grown on the W-doped interlayer shows a diamond Raman FWHM of 4.76 cm-1,a dislocation density reduced from 3.6×108 cm-2 to 6.9×107 cm-2,and an infrared transmittance of 61%.In contrast,the Ta-doped interlayer does not notably reduce the dislocation density and yields a lower transmittance of 54%.关键词
单晶金刚石/掺杂过渡层/同质外延/位错密度/微波等离子体化学气相沉积(MPCVD)Key words
single crystal diamond/doped transition layer/homogeneous epitaxy/dislocation density/microwave plasma chemical vapor deposition(MPCVD)分类
数理科学引用本文复制引用
徐孝勇,袁罡,朱俊奎,明森,马莉,彭国令,魏秋平..W,Ta掺杂过渡层的制备及其对 MPCVD单晶金刚石外延层质量的影响[J].金刚石与磨料磨具工程,2026,46(4):470-479,10.基金项目
国家十四五重点研究发展计划(2021YFB3701800) （2021YFB3701800）
国家自然科学基金(52071345) （52071345）
长沙市自然科学基金(kq2402226). （kq2402226）
