Prof. Naotaka Iwata Profile

Prof. Naotaka Iwata

at Toyota Technological Institute

SPIE Involvement:

Author

Publications (2)

SPIE Journal Paper | 4 September 2024

Electrical and structural properties of ArF excimer laser activation of Mg-doped GaN small area mesa device

Maria Emma Villamin, Ronel Christian Roca, Itaru Kamiya, Naotaka Iwata

OE, Vol. 63, Issue 09, 096101, (September 2024) https://doi.org/10.1117/12.10.1117/1.OE.63.9.096101

KEYWORDS: Laser irradiation, Annealing, Gallium nitride, Excimer lasers, Atomic force microscopy, Pulsed laser operation, Optical engineering, Magnesium, Laser processing, Semiconducting wafers

Read Abstract +

Laser activation annealing using of an Mg-doped GaN four-point probe small mesa device using a 193-nm ArF excimer laser 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. This method has several merits: (1) the four-point probe measurement allows accurate resistivity measurement of the GaN layer independently of the contact resistance, (2) utilizing a small area mesa also as the alignment marker during laser annealing ensures that the irradiated area precisely corresponds to the resistivity measurement area, and (3) multiple irradiation-measurement cycles are possible with a single mesa device, which avoids wafer-scale variations. The dependence of the resistivity to the laser fluence and irradiation time were investigated by multiple-irradiation measurement cycles to a single mesa device in combination with atomic force microscopy analysis for surface morphology characterization. Results reveal that laser annealing at 530 mJ/cm2 for 1500 s (at 150 Hz repetition rate) decreases the resistivity from 11.5 (before irradiation) to 5.6 Ω·cm (after irradiation). This value is similar to resistivity achieved by rapid thermal annealing (RTA) at 800°C for 120 s, suggesting successful Mg-doped GaN activation. Results also show stronger dependence on the irradiation time (temporal dependence) than the laser fluence, which may imply that activation mechanism for the laser annealing has a thermal contribution. This is the first report demonstrating ArF laser annealing that achieves a similar degree of activation with conventional RTA using resistivity measurements.

Proceedings Article | 8 March 2024 Poster + Paper

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

Maria Emma Villamin, Ronel Christian Roca, Itaru Kamiya, Naotaka Iwata

Proceedings Volume 12886, 128860F (2024) https://doi.org/10.1117/12.3002082

KEYWORDS: Laser irradiation, Annealing, Gallium nitride, Excimer lasers, Semiconducting wafers, Atomic force microscopy, Ultraviolet radiation, Sapphire, Resistance, Pulsed laser operation

Read Abstract +

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years