Extraction of Contact Resistivity for Transition Metal Oxide-Based Silicon Heterojunction Solar Cell

Author

Shanmugam K Mr, SASTRA Deemed to be UniversityFollow

Date of Award

10-3-2025

Document Type

Thesis

School

School of Electrical & Electroncis Engineering

Programme

Ph.D.-Doctoral of Philosophy

First Advisor

Prof.V.Muthubalan

Keywords

Contact Resistivity, Heterojunction Solar Cell, TiOx, TLM, CSM

Abstract

Contact resistivity quantifies the charge transport barrier, which is one of the key parameters for choosing the carrier selective contact for silicon solar cells. Optically transparent and electrically selective contacts such as Transition Metal Oxide (TMO)–based contacts are employed in solar cell applications. Therefore, extracting contact resistivity for such Schottky contacts requires apposite validation.

In this work, the contact resistivity of TiOx/LiFx/Al stack over an n-type c-Si wafer is extracted using two conventional techniques: i) Shockley’s Transfer Length Method (TLM) and ii) Cox and Strack Method (CSM). The extracted contact resistivity is validated by comparing it with the solar cell’s contact resistivity (true contact resistivity) using Sentaurus TCAD-based simulations. It is found that TLM overestimates the contact resistivity for highly resistive TiOx films due to the asymmetric nature of the TMO barrier, which is correlated with the reported experimental data.

In contrast, CSM extracts more accurate contact resistivity for TiOx contacts when total resistance is extracted closer to the Jmpp (38 mA cm-2). Besides, it is recommended to include the passivating layer along with the contacts (in case of passivating contacts) to extract the actual contact resistivity felt by the solar cell. This work is extended to propose a strategy for accurate extraction of the partial contact resistivity (𝜌𝑃𝐶 ) of a solar cell with Ohmic (or linear) and Schottky (or nonlinear) contacts. This work demonstrates how the CSM can accurately estimate the 𝜌𝑃𝐶 of a solar cell using Sentaurus TCAD-based simulations.

The simulation predicts that for linear contact solar cells, 𝜌𝑃𝐶 is approximately constant when the contact fraction is varied, whereas for non-linear contact, 𝜌𝑃𝐶 decreases with contact fraction as opposed to the previously reported works. The experimentally reported data is also shown to support the claim for the linear contacts further.

Despite the larger full-contact resistivity of non-linear contacts, the contact resistivity and fill factor (FF) of both linear and non-linear partial contact solar cell is almost similar to ~(3.5 − 5) 𝑚Ω 𝑐𝑚−2 and ~75% respectively, at a 0.3% contact fraction due to the decreasing contact resistivity with the contact fraction for non-linear contacts.

Recommended Citation

K, Shanmugam Mr, "Extraction of Contact Resistivity for Transition Metal Oxide-Based Silicon Heterojunction Solar Cell" (2025). Theses and Dissertations. 108.
https://knowledgeconnect.sastra.edu/theses/108