Calibration of boron concentration in CVD single crystal diamond combining ultralow energy secondary ions mass spectrometry and high resolution X-ray diffraction

详细信息    查看全文

• 作者：B. Guzmá ; n de la Mata ; A. Sanz-Hervá ; s ; M.G. Dowsett ; M. Schwitters ; D. Twitchen
• 关键词：Single Crystal Diamond ; Boron doping ; uleSIMS ; HRXRD
• 刊名：Diamond and Related Materials
• 出版年：2007
• 出版时间：April-July 2007
• 年：2007
• 卷：16
• 期：4-7
• 页码：809-814
• 全文大小：664 K

文摘

In this work, we combine ultralow energy secondary ion mass spectrometry (uleSIMS) and high resolution X-ray diffraction (HRXRD) for the analysis of boron doped single crystal diamond. CVD layers of nominal boron concentrations 1.3 · 10²¹ At/cm³, 2.0 · 10²¹ At/cm³, 6.9 · 10²¹ At/cm³ and 3.8 · 10²² At/cm³ have been characterized by uleSIMS at 1 keV, 500 eV and 300 eV using normal incidence O₂⁺ and by HRXRD.

We show that the enhancement of ¹²C⁺ signal as a function of boron concentration observed in uleSIMS analysis of heavily doped layers compared to intrinsic diamond is due to a change in the ionization probability for carbon rather than to a change in erosion rate or post-ionization in the gas phase. For this reason, calibrating the boron concentration using a relative sensitivity factor (RSF) derived from an implanted reference material, which will naturally have a different ionization probability for carbon, is not accurate and a calibration curve needs to be obtained from an independent analysis technique such as nuclear reaction analysis (NRA).

Simulation and measurement of HRXRD 113 asymmetric and 004 symmetric reflections have confirmed that the layers grew coherently to the substrate. The peak strain in the samples has been obtained from the HRXRD patterns by comparison between simulation and experiments, being 0.41 · 10^{− 3}, 0.43 · 10^{− 3} and 1.30 · 10^{− 3} for the first three samples. The peaks in the experimental profiles are broad compared to the simulations of uniform layers, which is explained by the graded composition of the layers, shown by the uleSIMS profiles.