Papers by Keyword: Transmission Line Model (TLM)

Abstract: To ensure maximum device current is supplied through a vertical device having a backside ohmic contact, the specific contact resistivity, ρ_c, must be well characterized as it constitutes a portion of the device resistance. While there are multiple approaches to deduce ρ_c, the transmission line model (TLM) remains a convenient choice because of its simplicity in terms of fabrication, measurement, and analysis. For thick substrates where mesa isolation is impractical, the circular transmission line model (CTLM) is an attractive path. In this study we propose an additional restriction on the CTLM design such that the ρ_c is readily extracted from a simple linear regression just as is the case in a linear TLM. We demonstrate the simplified method by extracting ρ_c of an ohmic contact to the c-face of 4H-SiC substrate.

Abstract: Ohmic properties, thermal stability and surface morphology of Al-based and non-aluminium metallizations are investigated in dependence on the annealing temperature and initial composition. Non-aluminium contacts show poor ohmic properties, while contact resistivity of 3.47x10-5 Ω.cm2 is achieved for Ti/Al/Ti/Au metallization with a former-Ti/Al ratio of (30 wt.% /70 wt.%). Thermal properties of the Al-based metallization are improved by application of Mo layer as a barrier under the upper Au film of the contact structure. These contacts show excellent thermal stability at operating temperatures as high as 400oC. The less Al amount in the contact composition and Mo barrier layer contribute to the smoother surface and better edge acuity.