ArF excimer laser activation of Mg-doped GaN small area mesa device

In this study, ArF laser activation annealing of an Mg-doped GaN four-point probe small mesa device is investigated. Fabricated mesa device has 2-μm-high small mesa structures with In/Au contacts formed using standard semiconductor device process. In our setup, the ArF excimer laser was directed onto the sample using a series of mirrors and was focused through an aspheric lens to the sample, which is mounted on to a movable stage. The mesa device and the laser were aligned while being viewed on the computer monitor screen using a UV CCD camera. The dependence of the resistivity to the laser fluence and irradiation time were investigated by multiple-irradiation measurement cycles to a single mesa device. Results reveal that laser annealing at 530 mJ/cm² for 25 min (at 150 Hz repetition rate) decreases the resistivity from 11.5 (before irradiation) to 5.6 Ω·cm (after irradiation). This value is comparable to resistivity achieved by RTA at 800 ◦C for 2 min, suggesting successful Mg-doped GaN activation.