Hall mobility, measurement Holes

Hall effect measurements indicate mobilities of— 10-1 cm2 V-Isec-1 for both electrons (Dresner, 1980) and holes (E>resner, 1983). Tiedje et al. (1981) have measured drift mobilities of 1 cm2 V-1 for electrons and 10-3 cm2 V-1 sec-1 for holes. However, Silver et al. (1982) have estimated that the electron mobility is s 100 cm2 V-1 sec-1 by using the reverse recovery technique. 

Hall effect measurements were used to investigate the electrical properties of the poly-Si films formed by the ALILE process. Due to the incorporated Al, the poly-Si films are always p-type. At room temperature, a hole concentration of 2.6 x 1018 run 3 and a hole mobility of 56.3 cm2 V 1 s 1 were determined [16]. Temperature dependent Hall measurements revealed both valence band conduction and defect band conduction (two-band conduction). For such highly doped material, the presence of a defect band conduction is expected. The Al concentration in the poly-Si films was measured by secondary ion mass spectroscopy (SIMS). An Al concentration of about 3 x 1019 cm 3 was found, which is about a factor of 10 larger than the... 

In hydrogenated amorphous silicon (a-Si H) mobility measurements are much more difficult to perform and to interpret for two reasons (1) the material has a disordered structure, and (2) undoped a-Si H is a photoconducting insulator whose transport properties have much in common with those of dielectrics. In many instances, even doped a-Si H may be very resistive compared with conventional semiconductors. Nevertheless, the Hall mobility can still yield valuable information about the bands involved in electron and hole transport. In this chapter some of the ideas that make the... 

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. 

The electronic quality of the layer was determined measuring the bulk minority carrier lifetime on a free-standing Si epitaxial layer passivated with a corona charged (Schofthaler et al. 1994) thermal oxide. From a measured Hall mobility of the holes of 186 cm A s, the bulk lifetime of (0.27 0.08) ps, a diffusion length of 11 pm for the electrons in the p-type Si could be estimated. The diffusion length of 11 pm was about double the epitaxial layer thickness of 5.8 pm. Therefore, the lAD method seemed suitable for the production of epitaxial Si solar cells (Krinke et al. 1999). 

This expression is especially applicable to semiconductors or semimetals. The symbols n and p represent the densities of electrons and holes, respectively p and Pp are the corresponding mobilities of the electrons and the holes. Thus, the Hall effect measurement is a valuable method, especially when associated with resistivity measurements, to determine the sign, the density and the mobility of the charge carriers in materials. 

Hall coefficient measurements on MIECs usually reveal the properties of the more mobile electronic (electron/hole) defects. These measurements can be done for different compositions. The composition can be conveniently altered by coulometric titration or via interaction with the gas phase. Hall coefficient measurements yielding the electron or hole concentration have been reported for MnO, AgjS, AgjSe, and AgjTe. ... 

Some silicides are superconductors with transition temperatures in a broad range of values [148, 149] and small electron-phonon coupling constants [144], Table 14.3 collects carrier concentrations for thin silidde films evaluated from Hall effect measurements. Most metallic silicides present both electrons and holes in approximately equal number and having the same characteristics, that is, mobility and carrier density. This behavior is traced back to the existence of two bands, one electron-Uke and one hole-hke, crossing the Fermi energy [150]. 

Fig. 9. Hole mobility versus temperature for an InP Zn epilayer grown by OMVPE. a) before any hydrogenation, b) after hydrogen plasma for 6 hours at 200°C followed by a 275°C, 5 min. annealing. After hydrogenation, the InP layer is highly resistive and Hall measurements are difficult. The slight annealing is performed to partially reactivate the zinc acceptors to a value of 1.3 x 1016 cm-3, which makes possible Hall measurements. J. Cheval-lier et al., Materials Science Forum, 38-41, 991 (1989). Trans. Tech. Publications Semicond. Sci. Technol. 4, 87 (1989). IOP Publishing Ltd.

Measurements of mobility in PS suffer from the fact that the number of free charge carriers is usually small and very sensitive to illumination, temperature and PS surface condition. Hall measurements of meso PS formed on a highly doped substrate (1018 cm3, bulk electron mobility 310 cm2 V-1 s-1) indicated an electron mobility of 30 cm2 V 1 s 1 and a free electron density of about 1013 cm-3 [Si2]. Values reported for effective mobility of electron and hole space charges in micro PS are about five orders of magnitude smaller (10-3 to 10 4 cm2 V 1 s ) [PelO]. The latter values are much smaller than expected from theoretical investigations of square silicon nanowires [Sa9]. For in-depth information about carrier mobility in PS see [Si6]. 

Five stages were resolved during interface formation in Yb/Si(lll) system by AES, EELS data and in situ Hall measurements. Some amplitude oscillations have been observed in sheet conductivity, hole mobility and surface hole concentration within the Yb coverage range below 6 ML. The conductivity oscillations are explained by transition from semieonductor-type conductivity at the first two-dimensional Yb growth stages to metal-like conductivity of 2D and 3D Yb silicide films. 

In general, only one mobile charge carrier, either electrons or holes, is present. In this case, by measuring both the conductivity, a, and the Hall coefficient, Ru, it is possible to determine the number of charge carriers and their mobility as ... 

The high quality of rubrene crystals has allowed detailed measurements of the transport characteristics, including the recent observation of the Hall effect [26]. Charge transport in rubrene single crystals, while trap-limited at low temperature, appears to occur via delocalized states over the 150-300 K temperature range with an (anisotropic) hole mobility of up to 20 cm /V s at room temperature [27,28]. 

According to studies of the temperature dependence of the electrical conductivity and the Hall effect of n-type samples in system 3, a weak variation in these properties with tenq>era-ture has been established, which indicates degeneracy of the electron gas and ionization of impurities, Similar measurements on p-type samples in the same system showed that there is a reversal of the sign of the Hall coefficient (at about 500 K), and a high ratio of the electron mobility to the hole mobility (B = 60-80) [7],... 

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. 

The Hall effect under pressure and at temperatures down to 2.5 K has been measured by Konezykowski et al. (1981) on IV SmS. The Hall effect is positive below lOK and shows a Steep rise with decreasing temperature at pressures above 1 GPa (lOkbar). In a log p versus 1/T plot one observes at 1 GPa a gap of 2meV when the formula exp A /2A b7 is used, which just means again that the gap at 1 GPA is already partially closed. Since the Hall effect is positive, this must be interpreted in a two band model of the hybridized f bands and it means that the mobility in the lower band with holes is larger than in the upper band with electrons. This, however, has already been concluded from the optical analysis of Travaglini and Wachter (1984b) where for the upper band a larger effective mass has been deduced than for the lower band. 

The measurement of the Hall effect is one of the most important characterization techniques for semiconductors, both in industry and research. Its importance is based on the possibility of determining the resistivity, the charge carrier density and mobility and furthermore the type of charge carriers (electrons, holes) in a comparatively simple and fast measurement. The knowledge of these fundamental parameters is a key to a better understanding of the electrical properties of a material and is an essential component of quality control in semiconductor production. 

One can easily see that if n p, Eh reduces to -1/ne. Hall measurements are easiest to interpret in doped materials when either n 3> p orn < p. Otherwise one is faced with four unknowns, which require other measurements to resolve. For example, except for the difference between electron and hole mobilities, the Hall effect would be zero for intrinsic materials. One can also see that doing Hall measurements as a fimction of temperature offers a means of determining the occupancy number and energy levels of the various impurity states in the freeze-out region through Equation 20.22. 

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