Carrier scattering mechanisms limiting mobility in hydrogen-doped indium oxide

Abstract

Hydrogen-doped indium oxide (IO:H) has recently garnered attention as a high-performance transparent conducting oxide (TCO) and has been incorporated into a wide array of photovoltaic devices due to its high electron mobility (>100 cm2/V s) and transparency (>90% in the visible range). Here, we demonstrate IO:H thin-films deposited by sputtering with mobilities in the wide range of 10–100 cm2/V s and carrier densities of 4 × 1018 cm–3–4.5 × 1020 cm–3 with a large range of hydrogen incorporation. We use the temperature-dependent Hall mobility from 5 to 300 K to determine the limiting electron scattering mechanisms for each film and identify the temperature ranges over which these remain significant. We find that at high hydrogen concentrations, the grain size is reduced, causing the onset of grain boundary scattering. At lower hydrogen concentrations, a combination of ionized impurity and polar optical phonon scattering limits mobility. We find that the influence of ionized impurity scattering is reduced with the increasing hydrogen content, allowing a maximization of mobility >100 cm2/V s at moderate hydrogen incorporation amounts prior to the onset of grain boundary scattering. By investigating the parameter space of the hydrogen content, temperature, and grain size, we define the three distinct regions in which the grain boundary, ionized impurity, and polar optical phonon scattering operate in this high mobility TCO.

Effect of Oxygen Source on the Various Properties of SnO2 Thin Films Deposited by Plasma-Enhanced Atomic Layer Deposition

“…Meanwhile, the SH-SnO 2 film showed two-fold higher hydrogen intensity than that of the SO-SnO 2 film due to hydrogen incorporation from H-containing species in H 2 O plasma. Notably, hydrogen impurity concentrations in various oxides influence the crystalline structure and electrical properties, like carrier mobility and concentrations [32][33][34]. For example, Husein et al reported that hydrogen-doped indium oxide films showed decreased electron mobility as the hydrogen content was increased to 5.7% [33].…”

Zr‐Doped Indium Oxide (IZRO) Transparent Electrodes for Perovskite‐Based Tandem Solar Cells

“…Polar optical phonon scattering has been generally proposed as the main contributor to phonon scattering in In2O3. [18,19] Using the approximation for polar optical phonon scattering,   T -p , we determined 0.24 < p ≤ 0.45 for the annealed IZRO sample (Figure 2d). This is lower than the p = 2.2 reported for unintentionally doped epitaxially grown In2O3 films.…”

Photo-engineered optoelectronic properties of indium tin oxide via reactive laser annealing

“…This causes the reduced oxygen content in the surface region, resulting in the formation of oxygen vacancies. 54 While the temperature within the film is high enough, oxygen atoms remain mobile, and they continue to be drawn towards this region resulting in the final increased oxygen gradient within the film. In the oxidising environment, however, the oxygen atoms that escape at the surface are quickly replaced with oxygen atoms from within the pressurised chamber.…”

“…Finally, it is important to note that annealing in hydrogen has a potential to promote hydrogen doping within the lattice. 54,55 This has been proposed to be a shallow donor that is more energetically favourable than oxygen vacancies. 56 The effect of H-doping during ReLA in 5% H2 in N2 may further enhance the carrier concentration modulation, but analysis of this mechanism is beyond the scope of this work.…”