Effect of impurity band conduction on the electrical characteristics of n-type CuInSe2

Abstract

The Hall effect and electrical resistivity of n-type CuInSe2 single crystals are measured between 4.2 and 300 K. Using a single conduction band model, the variation of the electron concentration with temperature above 100 K is explained in terms of the thermal activation of a shallow donor. The density of states effective mass me*=0.09me of the electrons, the activation energy of the donors around 7 meV, their concentration, and the compensation ratio are estimated. The temperature dependence of the electron mobility in conduction band is analyzed by taking into account the scattering of the charge carriers by ionized impurities and acoustic and polar optical phonon modes. The adjustable parameters, thus obtained, are compared with those reported earlier. On the other hand, by considering the two-band model with electrons in both the conduction and impurity bands, the change in the Hall coefficient with temperature between 300 and 40 K is explained. It is found that at the temperature where the Hall coefficient is maximum, the mobility in the impurity band is about 20% as compared to its value in the conduction band. The width of the impurity band is found to increase with increasing impurity concentration and the electron mobility below 20 K is explained by considering the effect of Mott-type variable range hopping conduction.

Charge carrier mobilities and dynamics in thin film compound semiconductor materials from transient Thz absorption

“…This value is very well comparable to values obtained from Hall measurements on n-type crystals and is much larger than mobilities obtained previously for polycrystalline CuInSe2 by Hall measurements. [5][6][7] In contrast, the photoconductivity spectrum for the Cu-poor CuInSe2 samples looks quite different and in fact cannot be described by the Drude formalism. [8] The real part of the photoconductivity increases with frequency while the imaginary part decreases.…”

Mechanisms of charge transfer and electronic properties of Cu2ZnGeS4 from investigations of the high-field magnetotransport

“…54 and references therein). Moreover, it has been even suggested in investigations of CuInSe 2 , that the dependence of R H ( T ) is not exponential at all, whereas the resistivity-like behavior with the same value of T 0 should be addressed only to the Hall mobility 81, 82 .…”

Electrical Properties of the Ordered Defect Compound CuIn3Se5

“…2 that the carrier concentration decreases with decreasing temperature and then starts to increase after going through a minimum. It is well known [21][22][23] that the carrier concentration in the conduction (valence) band increases whereas in the impurity band decreases with the increase of temperature. Furthermore, at a given temperature the total charge carrier concentration is the sum of those in the conduction (valence) and impurity bands at that temperature.…”