Schottky-type GaN-based UV photodetector with atomic-layer-deposited TiN thin film as electrodes

In this work, a GaN-based UV photodetector with an asymmetric electrode structure was fabricated by atomic layer deposition (ALD) of TiN layers. The thickness of the TiN can be monitored in situ by a quartz crystal microbalance(QCM) and precisely controlled through the modulation of deposition cycles. During theALDprocess, periodic variation in the QCMfrequency was observed and correlated to the physical adsorption, chemical bonding, and the excessive precursor exhaust, which included tetrakis(dimethylamino)titanium (TDMAT) and N sources. The asymmetric TiN/GaN/TiN photodetector showed excellent photosensing performance, with a UV-visible rejection ratio of 173, a responsivity of 4.25 A/W, a detectivity of 1.1x10(13) Jones, and fast response speeds (a rise time of 69 mu s and a decay time of 560 mu s). Moreover, the device exhibits high stability, with an attenuation of only approximately 0.5% after 360nm light irradiation for 157 min. This result indicates the potential of TiN as a transparent contact electrode for GaN-based optoelectronic devices. (C) 2022 Optica Publishing Group

Automated summary

In this work, a GaN-based UV photodetector with an asymmetric electrode structure was fabricated using TiN as a transparent contact electrode. The device showed excellent photosensing performance, fast response speeds, and high stability.