Temperature behavior and modeling of ohmic contacts to Si implanted n-type GaN

The behavior of an ohmic contact to an implanted Si GaN n-well in the temperature range of 25-300 °C has been investigated. This is the sort of contact one would expect in many GaN based devices such as (source/drain) in a metal-oxide-semiconductor transistor. A low resistivity ohmic contact was achieved using the metal combination of Ti (350 Å)/Al (1150 Å) on a protected (SiO₂ cap) and unprotected samples during the post implantation annealing. Sheet resistance of the implanted layer and metal-semiconductor contact resistance to N⁺ GaN have been extracted at different temperatures. Both, the experimental sheet resistance and the contact resistance decrease with the temperature and their characteristics are fitted by means of physical based models.