Low Barrier Height Ohmic Contacts to Semiconductor Substrates
Original Publication Date: 1978-May-01
Included in the Prior Art Database: 2005-Feb-20
When ohmic contact is made to a heavily doped semiconductor (i.e., 10/21/ atoms/cm/3/, the choice of contact metal is relatively unimportant since, regardless of the resulting barrier height, the depletion width will always be small enough so that requisite tunneling is possible. As the semiconductor doping decreases, however, the depletion width increases, and it then becomes important to choose a metal whose work function results in a low barrier height if a good ohmic contact is required. An example is the case of a PtSi contact to P-type (5 x 10/18cm/3/) Si. PtSi has the highest reported barrier height to N-type Si (0.85 V) and, therefore, the lowest barrier height (0.25 V) to P-type Si. PtSi is used in these contacts primarily for this reason.