Semiconducting diamond

Note Electronic conductivity, and even superconductivity at ca. 10 K, was observed with a new carbon polymorph, buckminsterfullerene, synthesized in 1990. Electrochemical and photoelectrochemical properties of a semiconducting diamond electrode were studied by Pleskov.)... 

Measured rumpling amplitudes of Sn surface alloys on the (111) surfaces of Ni, Cu, Rh and Pt in a similar format to table 2. Note that Sn atomic radii corresponding to half the Sn-Sn distances are given for both semiconducting diamond-structure a-Sn and tetragonal p-Sn which is the stable phase at room temperature. 

Due to its transparency to UV-radiation, IR-radiation and visible light, diamond can be utilized as a coating material for optical components. Semiconducting diamonds (doped with boron, beryllium or aluminum) are utilized in special thermistors for the temperature range -200 to -i-500°C. 

In the case of semiconductors, it was first shown in this laboratory that the arrangements of the atoms in the surface monolayers of (100) and (111) germanium and silicon are not the same as those for these planes in the bulk (25). The altered arrangements were revealed by the presence of fractional order beams for the surface gratings in certain azimuths. This was later found to be the case for all crystals tested which have a diamond-type lattice, including semiconducting diamond and several of the intermetallic compounds. The surface structure of silicon was observed to be much more complex than that of germanium. In some azimuths, several fractional orders less than one-half were observed. 

Diamond without any defects is an electric insulator with a band gap of 5.5 eV. The specific conductivity of such isolating material is 8 x 10- Q- cm- , whereas for semiconducting diamond of type Ilb it is about 10- Q- cm- . 

GE reported the discovery of natural semiconducting diamond in 1952 [31]. Presently, hot filament CVD and microwave plasma assisted CVD (MPACVD) produce polycrystalline or diamond carbon (DLC) films at 1-10 pm/h on a variety of substrates. However, true epitaxial growth presently is not routinely achievable at this time. Diamond substrates also are not readily available making large area lattice matched depositions a problem. Typieal substrates are Si, sapphire and even copper. Boron is an effective p-type dopant, but there is no successful n-type dopant, although As, Li, O, P and Sb have been tried. 

Boron is often added in the form of a stable metal boride to gettered reaction volumes, to generate blue semiconducting diamonds (type Ilb) [62]. 

Structure. The use of synthetic semiconductive diamond thin films in electrochemistry has only recently been reported. Former designations such as diamondlike carbon (DLC) are now obsolete and so are not used in this book. By contrast with its other carbon allotropes, in diamond each carbon atom is tetrahedrally bonded to four other carbons using sp -hybrid orbitals. 

Further development of the indentation depth measurement method seems to be imminent when semiconducting diamonds are cut to the Vickers geometry and used to indent conducting specimens. At the moment the samples tested have been metals, but many special ceramics like TiC, TiN, SiC, and MWO3 are electrically conducting and could be investigated. The method involves sensitive measurement of electrical resistance as a function of indenter load. 

Okino, R, Shibata, H., Kawaguchi, Y. et al. (2004) Preparation of boron-doped semiconducting diamond films using BF3 and the electrochemical behavior of the semiconducting diamond electrodes. J. Fluorine Chem, 125, 1715. 

Figure 1 Hole concentration as a function of reciprocal temperature for a natural semiconducting diamond containing 8.3 X 10 cm acceptors and 4.2 X 10 cm" donors. (From Ref. 29.)...

Figure 6 Edge emission spectra at 77 K for (a) a high-purity synthetic diamond and (b) a natural semiconducting diamond. (From Ref. 60.)...

In natural semiconducting diamond it has been demonstrated that the blue cathodoliunines-... 

Semiconducting Diamond and Diamond Devices Table 1 Typical Semiconductor Properties... 

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