| Diamond is a kind of limited functional material in the region of mechanics, thermology, optics, chemic and electronics. Theoretically, properties of diamonds could be changed by doped. Smaller boron atom can easily enter diamond. After boron atom enter diamond's crystal lattice, the structure and character will be changed. The content of boron in diamond will be changed when the synthesis and doping boron methods are difference. Diamond changed from insulator to p-type semi-conductor via boron doped. By addition of different contents of boron carbides in the iron-based catalysts, the boron-doped diamond single crystals had been synthesized under high pressure and high temperature.The morphology, structure, electronic properties, annealing properties and thermalstability of diamond single crystals with boron-undoped and different boron concentration were systematically studied using Optical micrograph (OM), Scanning electron microscope (SEM), X-ray diffraction (XRD), Raman spectrum (Raman), Field emission scanning electron microscope (FESEM), Cathodoluminescence spectroscope(CL), Different thermal analysis (DTA),etc. Some significant explorations were proceeded about the influence cause on boron-doped diamond single crystals and the relevance of structure and property. The major research efforts of the present study are as follows:(1) The change of (100) facets and (111) facets is different with the process of boron doped. There's lots of etch pits on (100) facets, etch pits are tetragonal pyramid or retiform shape. Boron assembles on (111) facets and formed zigzag dislocation, hampered the growth of (111) facets, proportion of it has increase, and there's an enrichment on (111) facets.Raman spectrum of boron doped diamonds illustrate that the broadening of full width at half maximum (FWHM) is stem from the increase of defects in diamond. The well-distributed broadening of FWHM is the evidence of boron well-distributed in diamonds crystal lattice.(2) Morphology and structure is not the same in different crystalface of diamond after boron doped via cathodoluminescence detect. Cathodoluminescence intensities increased on (100) facets with the increase of boron content in catalyst, and there appeared another acceptor level. High-energy peaks emerge after boron doped. It can be taken as impurity peaks due to the doped of boron. Cathodoluminescence intensities increased on (111) facets with the increase of boron content in catalyst, the growth rate low-energy peak is much faster and the intensity is much stronger than that of (100) facets. It's easier for boron aggregation on (111) facets, there's more hole and carrier.(3) The number of holes and carriers increased with the increase of boron content in catalyst, it conduce the change of structure and electronic properties of diamonds. Resistance of diamonds have a transition between boron content of 2a-3a, which enable electronic properties of diamonds into semiconductor domain. It's viable for diamond semiconductor device of boron content of acceptor impurity is 2a～5a.(4) Annealing is good for the improvement of electronic property of diamond from the analysis of CL spectra. CL spectra intensities increase with the heightening of annealing temperatures. Both of the characteristic peak of (100) facet is in the range of band A emission while the high-energy peaks is in the range of band A emission and weak-energy peaks is in the range of Mossbauer emission of (111) facet after annealing process.(5) The oxidizing temperature of boron-doped diamond increased approximately 100℃through the thermal analysis. The temperature of 10% weightlessness rate increases with the content of catalyst boron and decreases later. |
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