Hall measurement diamond

The electrical properties of single crystal diamond will be useful to study those of heteroepitaxial diamond films. As a reference. Figures 13.1 (a)-(c) show the resistivity, mobility, and carrier density of single crystal diamond as a function of temperature [107]. Figures 13.2 (a) and (b) are the resistivity and mobility as a function of the carrier density. A more thorough study on B-doped homoepitaxial diamond is presented in Ref. [416], where AFM observation of the layer surface. Hall measurements at different temperatures, and other data are presented. 

Figure 6 shows Hall measurement data for a series of boron-doped nanocrystalline diamond films deposited with different levels of B2H6 added to the source gas mixture. Measurements of the carrier concentration and mobility were made at different temperatures up to about 500°C. At room temperature, the carrier concentration increases and the hole mobility decreases as B2H6 added to the source gas mixture with values in the range of 10 -10 cm and 10-100 cm /V-s, respectively. The carrier concentration and the doping level increase proportionally with B2H6 added. 

From the experimental side, the band-structure parameters are mainly determined from the cyclotron resonance (CR) spectra of electron and holes (see for instance [4]). Some of these parameters can also be obtained from the Zeeman splitting of electronic transitions of shallow impurities involving levels for which the electronic masses can be taken as those of free electrons or holes, or from the magnetoreflectivity of free carriers. Average effective masses can also be deduced from the Hall-effect measurements or from other transport measurements. Calculation methods that have been used to obtain band-structure parameters free from experimental input are the ab-initio pseudopotential method, the k-p method and a combination of both. These theoretical methods are presented in Chap. 2 of [107]. VB parameters at k = 0 including k and q have been calculated for several semiconductors with diamond and zinc-blended structures by Lawaetz [55]. 

A good linear correlation was found between the integrated absorption of the strongest RT line centred at 347 meV and the neutral acceptor concentration obtained from Hall effect measurements of five natural lib diamonds [43]. This was later converted into a RT calibration factor of this band of 1 x 1014 cm-1, assumed to be valid for B concentrations up to a few 1018 cm-3. For larger B concentrations going up to 1 x 102°cm 3, a calibration factor of about one order of magnitude larger was obtained by correlation with SIMS measurements on CVD diamonds [64], These calibration factors are discussed in the review by Thonke [177],... 

The electrical properties of the diamond films or free-standing discs are largely determined by the boron-doping level. Resistivities of useful diamond OTEs are in the range of 0.5-0.05 H-cm. Boron-doping levels associated with this resistivity are ca. 1-10 x 10 B/cm, as determined by boron nuclear reaction analysis measurements. Very preliminary Hall effect measurements for the diamond/quartz (Fig. 23A, 2) and diamond/ Si (Fig. 23B, 7) OTEs have revealed carrier concentrations between 10 and 10 cm and carrier mobilities (holes are the majority carrier in boron-doped films) of 1-100 cm /V-s. 

Visser et al. (41) also carried out Hall effect measurements as a function of temperature. They found that they could not fit the data using Eq. (1) with the effective mass value m = OnSnit used for natural type lib diamond (Sec. II.B). For their most lightly doped 100 sample they found m = 0.35 Je and = 0.008. The room-temperature carrier concentration and... 

The intensity of the bound-exciton peaks, relative to that of the free-exciton features, gives an indication of the uncompensated boron concentration in the region of the diamond examined. For the diamond shown in Fig. 6b this is about 5 X 10 cm as determined from Hall effect measurements (31). A very weak peak D, due to the accidental presence of a small concentration of boron (estimated as 3 X 10 cm ), is also evident in the low-temperature spectrum in Fig. 5. 

After calibration, the carrier concentration for metallic diamonds can therefore be more conveniently derived from Raman measurements, from the precise position of the 500-cm i peak than by Hall-effect measurements, which require metallic contacts and a magnetic field, or hy SIMS, which destroys the films and measures the total concentration of boron in the grains as well as in the grain boundaries. 

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