Optical Conductivity Studies in Heavily Boron-Doped Diamond

Abstract

Subject classification: 78.30.Am; 78.66.Db; S5The optical transmittance and reflectance of heavily boron-doped (2 Â 10 20 cm --3 < [B] < 2 Â 10 21 cm --3 ) epitaxial diamond layers deposited by MPCVD were measured in the infrared range. While T-dependent measurements confirmed the metallic character of such films, the overall spectral features were well reproduced by introducing Drude components in the fitting expression for the optical conductivity. The associated microscopic transport parameters were quantitatively compared to those resulting from preliminary transport measurements performed on the same samples. We show that room-temperature FTIR reflectance measurements provide an easy contactless characterization of the transport properties of such p + films, and we discuss what new information on carrier-phonon interaction as well as on the transport mechanism in the impurity band might be gained from temperature-dependent spectroscopic data.

Optical and electronic properties of heavily boron-doped homo-epitaxial diamond

“…3 Chemical and structural properties The average solid state boron concentrations [B] reported in Fig. 1 correspond to SIMS profiles very similar to those already published [35] except for a 25% upward correction of the absolute value resulting from a more recent calibration specific to samples where [B] > 10 20 cm -3 and for which a Ib {100}-oriented substrate has been implanted off-axis with 10 15 cm -2 B ions at 90 keV. As seen on Fig.…”

“…This difficulty can be circumvented by growing much thinner films or by using reflection geometries as described below. In a previous work [35], it was established that the reflectance spectra of monocrystalline p + diamond layers in the mid-infrared yielded the typical plasmon edge associated to the collective excitation of free holes in the semiconductor.…”

Metal-to-insulator transition and superconductivity in boron-doped diamond

“…Considering that l mfp /x/l L , it was concluded that boron-doped superconducting diamond was in the dirty limit. Similar conclusions may be drawn from a free-electron description of the room-temperature macroscopic conductivity values measured on superconductive films (usually in the 200-2000 U K1 cm K1 range), from momentum distribution curves of angle-resolved photoemission around the Fermi level (which yielded l mfp Z0.5 and 0.9 nm in Yokoya et al (2005)), or from a Drude model analysis of their reflectivity spectrum (microscopic optical conductivity) yielding l mfp Z2.5 and 4 nm at room temperature (Bustarret et al 2001;Mareš et al 2006). The latter values were obtained on the same epilayers mentioned above for which a phase diagram was published and x values of 15 and 20 nm have been proposed (Bustarret et al 2004): again here, l mfp /x.…”

Boron-doped superlattices and Bragg mirrors in diamond

“…In this work, we propose to consider diamond heavily boron-doped at concentrations [B] larger than a few 10 20 cm À3 as a metallic diamond (p þ ) alloy. The difference in refractive index (index contrast) between p þ single crystal epilayers and non-intentionally doped ([B] < 10 17 cm À3 ) diamond (i) layers increases with wavelength [7][8][9] (around 10% at 600 nm and 20% at 800 nm), along with the absorption coefficient related to the plasmon oscillations present in p þ diamond. Despite these limitations, we shall demonstrate in the following that it is possible to make Bragg mirrors out of diamond by alternating the growth at two different doping levels, and to tune their periodic refraction properties to the emission wavelengths of a specific color center.…”

“…3), and only slightly stronger than that of a thick p þ material. 7,8 With a Bragg peak maximum at 30%, this contributed to the enhancement of the mirror efficiency and wavelength selectivity. Furthermore, the sharper reflectance drop on the long wavelength side of the peak was found well suited to cutting off the broad phonon related side bands from the sharper zero phonon line emission of NV centers.…”