Low-field transport

Hall effect is the most widely used technique to measure the transport properties and assess the quality of epitaxial layers. For semiconductor materials, it yields the carrier concentration, its type, and carrier mobility. More specifically, experimental data on Hall measurements over a wide temperature range (4.2-300 K) provide quantitative information on impurities, imperfections, uniformity, scattering mechanisms, and so on. The Hall coefficient and resistivity (p) are experimentally determined and then related to the electrical parameters through (for n-type conduction) ffn = fulne and M-h = f n/P. where n is the free electron concentration, e is the unit electronic charge, Ph is the Hall mobility, and Th is the Hall scattering factor that depends on the particular scattering mechanism. The drift mobility is the average velocity per unit electric field in the limit of zero electric field and is related to the Hall mobility 

The major scattering mechanisms that generally govern the electron transport in 

III-V semiconductors are also valid for ZnO. They are briefly listed as follows  

Experimental investigation of the temperature-dependent carrier mobility and concentration can be used to determine the fundamental material parameters and understand the carrier scattering mechanisms along with an accurate comparison with theory. Table 1.12 gives the selected best values of electron mobility and corresponding carrier concentration in bulk and thin-film ZnO grown by various techniques. Even today, the electrical properties of ZnO are hard to quantify experimentally due to varying quality of the samples available. 

Sample FWHM ofXRD rocking curves (arcsec) Carrier concentration (cm- ) Electron mobility (cm V s ) References 

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