Electrical conductivity of plasma-deposited carbon–germanium amorphous semiconductors: correlation with nanostructure

Insulator coated metal nanoparticles with a core/shell geometry exhibit a temperature sensitivity similar to advanced spinels

“…For materials with a smaller bandgap, the electron transport can be described by the variable range hopping mechanism (VRH) [43]. The corresponding experimentally determined values of n depend mainly on the conducting phase material and its characteristic dimension [44]. In the case of polymers filled with carbon black n varies in the range of 0.5-0.75 [45,46].…”

Transition from amorphous semiconductor to amorphous insulator in hydrogenated carbon–germanium films investigated by IR spectroscopy

“…As a result, the density of amorphous germanium clusters is sufficient to influence the material electronic structure [7]. This hypothesis has been strongly supported by impedance spectroscopy measurements carried out over a broad range of temperatures [3]. It has been found that the electrical conductivity dependence on temperature and frequency fits the hopping model, which is common for percolation transport in heterogeneous systems.…”

“…Carbon can exist in sp 3 in the films is necessary for better understanding of the role of hydrogen in various sp2 and sp3 bonds in these films [11]. A common feature for all the films is a broad absorption band centered on 3000 cm À1 attributed to the stretching CH bond in its various configurations (Fig.…”

“…It was also shown that a-Ge clusters form larger domains (size of about 100 nm). Inside these domains charge transfer is more efficient than between neighboring domains, hence the last one is responsible for dc conductivity [3]. This specific nanostructure of a-S films deposited from TMGe seems to be particularly interesting due to its possible application in the area of nanocatalysis.…”

“…tetramethylgermane -TMGe) [1,2]. The differences between a-S and a-I films can be illustrated by a comparison of values: specific electrical conductivity (10 À4 S/m and 10 À18 S/m) [3], transport gap (0.3 eV and 0.9 eV) [2] and optical gap (2 eV and 3.2 eV) [1]. This spectacular change of electronic structure can be caused by a small variation of plasma deposition parameters that are responsible for the impact energy of ions bombarding surface of the growing film [4].…”