Evaluation of Sn-Doped Indium Oxide Film and Interface Properties on a-Si Formed by Reactive Plasma Deposition

Abstract

In pursuit for the improvement of heterojunction Si solar cell performance, we evaluated Sn-doped Indium oxide (ITO)/a-Si structure by using conventional and hard X-ray photoelectron spectroscopy (XPS, HAXPES) to identify the cause of solar cell performance degradation. HAXPES allows us to evaluate the SiOx layer at the ITO/a-Si interface non-destructively. The SiOx formation at the ITO/a-Si interface leads to an increase the contact resistance, which can be reduced by post deposition annealing (PDA). In addition, PDA promoted the evaluation of Fermi level, the precipitation of ITO component in a-Si layer, and the increase of interface roughness. Before PDA, the diffusion of Sn atoms in a-Si was observed. Furthermore, it was also confirmed by PDA that Si atoms were diffused to ITO. These reaction at the ITO/a-Si interface may be part of the degradation factor of the Si solar cells.

Investigation of the Chemical Reaction between Silver Electrodes and Transparent Conductive Oxide Films for the Improvement of Fill Factor of Silicon Heterojunction Solar Cells

“…In the previous study, we have reported that the oxide layer formed during TCO deposition was a factor in increasing contact resistance. 24 In addition, we found that the amount of oxide layer formation differs between IO:H and 10 wt% Sn-doped ITO. For IO: H films, the oxide layer formation was suppressed by heating process prior to the film deposition.…”

Evaluation of plasma induced defects on silicon substrate by solar cell fabrication process

“…If the ITO layer is deposited on a-Si, Sn diffusion or In precipitation on the substrate may occur, which may make it difficult to clearly evaluate damage on the Si substrate. 28) Moreover, it is extremely difficult to clarify the damages on a-Si itself. Therefore, the ITO layer was deposited directly on the substrate.…”

Hard x-ray photoelectron spectroscopy: a snapshot of the state-of-the-art in 2020

“…Laboratory-based HAXPES systems have exploited the accessibility of additional, deeper core levels to study depth-dependent phenomena in both bulk as well as multilayer systems. [85][86][87][88][89][90][91] A general advantage not just of laboratory systems, but any HAXPES experiment, is the ability to access deeper core levels opening up new experimental and analytical strategies. [43,[92][93][94][95] Figure 4 gives a schematic overview of core levels of transition metals and lanthanides that become available when moving A c c e p t e d M a n u s c r i p t…”

“…Results on Si-based and post-transition metal oxide device multilayers and transistor structures have demonstrated the ability to probe the core level spectra of buried layers and extract information on their chemical state in-situ without the need of sputter depth profiling as is necessary in SXPS studies. [87,88,100] A recent study on SiC/SiO 2 device multilayers, which are used for power electronic applications, has also demonstrated the opportunity to target specific interface states related to defect states at semiconductor-dielectric interfaces. [89] Several of the studies mentioned here also exemplify the complementarity of laboratory-and synchrotron-based HAXPES systems to enable a comprehensive and efficient exploration of samples of interest.…”

“…[89] Several of the studies mentioned here also exemplify the complementarity of laboratory-and synchrotron-based HAXPES systems to enable a comprehensive and efficient exploration of samples of interest. [85,87,89,106] In contrast to synchrotron-or FEL-based HAXPES, the excitation energy in laboratory-based HAXPES systems is fixed to the characteristic X-ray emission of the anode material. This has important implications for the information depth (see general discussion on this topic in Section 3.1.1.…”