Quasi-two-dimensional transmission line model (QTD-TLM) for planar ohmic contact studies

An analytical quasi-two-dimensional transmission line model (QTD-TLM) has been formulated to more accurately extract the specific contact resistance (p,) of ohmic contacts than the conventional one-dimensional TLM (1D-TLM). Similar to 1D-TLM, the extraction of p, using QTD-TLM is straightforward. By means of the conformal mapping technique, the two-dimensional (2-D) (or lateral) current flow and current crowding, owing to the presence of a gap between the TLM mesa and contacts, are jointly incorporated into our model using a single shunt resistor. QTD-TLM is generalized as it is applicable to a variety of contact dimensions and gap widths, and to both alloyed and nonalloyed contacts. The validity of QTD-TLM has been verified experimentally using two alloyed and two nonalloyed ohmic contacts, and by comparison with results from a 2-D numerical model.