S. K. Karna, Y. K. Vohra, P. Kung, S. T. Weir
The boron-doped single crystal diamond films were grown homoepitaxially on synthetic (100) type Ib diamond substrates using a microwave plasma assisted chemical vapor deposition. A modification in surface morphology of the film with increasing boron concentration has been observed using atomic force microscopy. Use of nitrogen during boron doping not only improves the surface morphology but also increases the growth rate significantly. However, use of nitrogen during boron doping lowers conductivity of the film. The color of the films was observed to be changing with boron contents in the film. A few additional bands at the lower wavenumber regions along with the zone center optical phonon mode for diamond were visible in Raman spectra. The change in the peak profile of the zone center optical phonon mode and its downshift were observed with the increasing boron content in the film. P-type doping was verified from Hall measurement. In the experimental temperature range films showed two different conduction mechanisms. The transition temperature from band to hopping conduction was observed to shift towards lower temperature with increasing boron contents in the film. In the most heavily doped sample the room temperature resistivity was measured to be 0.12 {\Omega}cm and transition temperature to be ~240 K.
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http://arxiv.org/abs/1301.7721
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