Abstract:Electric transport properties measured by Van der Pauw resistivity experiments of Low-Temperature Molecular Beam Epitaxy (LT-MBE) GaAs samples are used to identify a method to improve the resistivity of GaAs material. We present results on five samples grown at 265, 310, 315, 325, and 345 o C. The electric measurements were carried out at temperatures ranging from 130 to 300 K. In this temperature range the dominant transport process is identified as variable range hopping. The hopping parameter plotted agains… Show more
“…Chaudhuri et al [27] observed the VRH mechanism in n-type GaAs below 40 K. But Rodriguez et al [28] observed the VRH mechanism in CuInTe 2 in the temperature range 53-95 K, a relatively high temperature range. Rubinger et al [29] observed the VRH mechanism at even higher temperatures, 130-300 K, in semiconducting GaAs prepared by molecular beam epitaxy.…”
“…Chaudhuri et al [27] observed the VRH mechanism in n-type GaAs below 40 K. But Rodriguez et al [28] observed the VRH mechanism in CuInTe 2 in the temperature range 53-95 K, a relatively high temperature range. Rubinger et al [29] observed the VRH mechanism at even higher temperatures, 130-300 K, in semiconducting GaAs prepared by molecular beam epitaxy.…”
“…Temperature dependence of the electric resistivity ρ indicated the semiconductor-like behavior as shown in Figure , that is, ρ was increased with decreasing temperature, and the magnitude of ρ at room temperature (ρ RT ) showed a tendency to decrease with increasing the boron concentration in the composite rod for the sample preparation (see inset in Figure ). The latter tendency can be considered as a result of increasing the metallic character of individual MWNTs, and the mechanism of the former temperature dependence can be explained by the Mott's variable range hopping (VRH) conduction, which is frequently seen in the assembly of the small conducting materials or particles. − 1 Temperature dependence of the electric resistivity ρ for the pellet-formed MWNTs. Explanation of the sample codes (B0NT, B5NT, and so on) is in the text.…”
Temperature dependence of the electric resistance was measured in the temperature range between 5 and 290
K for the assembly of the boron-doped multiwalled carbon nanotubes (B-doped MWNTs). The observed
temperature dependence was explained by the mechanism of three-dimensional variable-range hopping (3D-VRH) conduction, and the characteristic temperature T
0 of 3D-VRH was varied between 1.5 and 625 K. This
change of T
0 was systematically explained by the change of the electronic density of states at the Fermi level
N(0) of B-doped MWNTs. In addition, the boron-doping-induced electron spin resonance (ESR) signals were
detected at g = 2.001 and 2.002, and the relative values of the ESR intensities were consistent with the
enhancement factors of N(0) derived from 3D-VRH. These facts were explained by the substitutional doping
of the boron atoms to the sp2-bonded carbon network that organizes the nanotube wall.
The photo-excitation effect on the current transport mechanism in TlInS 2 crystals has been studied by means of dark and illuminated conductivity measurements. The temperature-dependent electrical conductivity analysis in the temperature region of 110-340 K revealed the domination of the thermionic emission and the thermally assisted variable range hopping (VRH) of charge carriers above and below 160 K, respectively. Above 160 K, the conductivity activation energies in the dark are found to be 0.28 and 0.15 eV in the temperature regions of 340-240 K and 230-160 K, respectively. In the temperature region of 110-150 K, the dark variable range hopping analysis revealed a density of localized states of 1., an average hopping distance of 0.53 nm and an average hopping energy of 79.65 meV. When the sample was photoexcited, the values of the conductivity activation energies, the density of localized states near the Fermi level and the average hopping energy were observed to decrease sharply with increasing illumination intensity. On the other hand, the average hopping distance increased with rising illumination intensity. Such behaviours were attributed to the Fermi level shift and/or trap density reduction by electron-hole recombination.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
