An improved transmission line structure for contact resistivity measurements

Abstract The accuracy of the conventional Transmission Line Method (TLM) which is used for measuring specific contact resistivity is sensitive to the sheet resistance of the contact metallisation and to variations in probe placement positions. Furthermore if end-resistance measurements are used to determine the modified sheet resistance (Rsk) under the contact pad these problems may be exacerbated. We propose an alternative TLM structure that avoids these difficulties. Both metallisation sheet resistance and modified sheet resistance are included in the model. The validity of this approach is verified by examining experimental results for AuGeNi contacts on n+ GaAs, using both the conventional and alternative TLM techniques and demonstrating improvements in accuracy and consistency.