Power transfer-length method for full biasing contact resistance evaluation of organic field-effect transistors

A development of the conventional transfer-length method (TLM) for organic transistors’ contact resistance evaluation is proposed. By adding the dissipated power in access resistance and in the channel, we found that TLM can be extended to the non-linear region, i.e., up to saturation regime, which is widely believed to be a barrier for TLM application now. To improve the extraction accuracy and stability, a modified TLM version is used for the operation at small gate voltages. This modified power TLM is applied to polymer and pentacene field-effect transistors and proved as a useful tool for the contact resistance evaluation as a function of gate and drain voltages from common current–voltage characterizations.

Contact resistance of organic field-effect transistors can be extracted by a power TLM with respect to the drain voltage. The contact resistances of top-contact and bottom-contact pentacene transistors are found to behavior quite differently against the gate voltage and the drain voltage. This power TLM enables a full range of gate/drain voltage contact resistance evaluation by means of common current–voltage characterizations.Figure optionsDownload as PowerPoint slideHighlights
► Estimation of dissipated power demonstrates the possibility of power-TLM extraction.
► Output resistances in non-linear regime exhibit linear variation with channel length.
► The modified power-TLM improves the extraction stability and reliability.
► Modified power-TLM well extracts contact resistance at overall drain/gate voltage.