Influence of dopant segregation on the work function and electrical properties of Ge-doped in comparison to Sn-doped In₂O₃thin films

Abstract

Ge‐doped In2O3 thin films prepared by magnetron sputtering are studied using photoelectron spectroscopy and Hall effect measurements. Carrier conductivities of up to 8.35thinmathspace×thinmathspace103cm−1 and carrier mobilities of up to 57thinmathspacecm2thinmathspaceV−1s−1 are observed. The surface Ge concentration is enhanced by a factor of 2–3 compared to the concentration in the interior of the films. The surface Ge concentration increases with more oxidizing deposition conditions, in opposite to what has been reported for Sn‐doped In2O3. Ge‐doped In2O3 films exhibit higher work functions as compared to Sn‐doped films, in particular at oxidizing conditions. This is attributed to the formation of a GeO2 surface phase. While segregation of Sn reduces the carrier mobility due to grain boundary scattering, Ge segregation does not show such an effect. The differences are attributed to the different oxidation states of the segregated dopants, in agreement with the observed dependence of segregation on oxygen activity.

Materials for Transparent Electrodes: From Metal Oxides to Organic Alternatives

“…All the examples given in this section so far concerned Sn doped indium oxide, as it is currently the benchmark materials for inorganic transparent electrodes. However, it has been shown that indium oxide can also be efficiently doped by other elements such as Si, Ga or Mo [34][35][36][37] .…”

“…Gallium doped In2O3 for instance, was reported to display conductivities in the range of 10 3 to 10 4 Scm -1 and extremely high electron mobilities of 50 cm 2 V -1 s -1 [34,36,37] , whereas doping of In2O3 with molybdenum resulted in improved transmittance in the visible regime as compared to tin doped InO [35] . deposited via an aqueous sol-gel process.…”

Interface Behaviour and Work Function Modification of Self-Assembled Monolayers on Sn-Doped In2O3

“…Nevertheless, according to DFT calculations [28][29][30]33], one would expect some differences between [110]and [111]-oriented films, which both exhibit flat surfaces. A possible explanation for the independence on surface orientation is the segregation of the Sn dopant to the surface, which is particularly observed under reducing conditions [34][35][36]. A different surface composition will affect the surface dipole.…”

“…Significant difference of the ionization potential I P , which is the difference between the valence band maximum and vacuum energy, between the [100] and [111]-surfaces of In 2 O 3 could be observed as well [29]. The situation is more complex for doped In 2 O 3 due to dopant segregation [30,[34][35][36]. Some authors [17,37] suggested that a surface treatment of the substrate may enhance the stability of the organic molecules.…”

Thermoelectric properties of Zn- and Ce-alloyed In2O3 and the effect of SiO2 nanoparticle additives

“…The electrical conductivity can be significantly enhanced to approximately 1000 S cm −1 by alloying with Sn, which is known as indiumtin-oxide (ITO). There are also reports on the improvement of electrical conductivity by alloying with different elements, such as Ti [29], Ge [30], and Mo [31]. However, the thermal conductivity of In 2 O 3 -based materials is generally high, which is an obstacle for thermoelectric applications.…”