Near-Ultraviolet Lateral Photovoltaic Effect with Ultrafast Optical Relaxation Time in Titanium Nitride/Silicon Heteroepitaxial Junctions

Lateral photovoltaic effect (LPE)-based silicon (Si) position-sensitive detectors suffer from low light absorption efficiency and weak photoelectric response in the ultraviolet (UV) and other short-wavelength ranges due to the indirect bandgap characteristics of Si, which severely limits their application in high-sensitivity UV detection and positioning.In this study, titanium nitride (TiN) thin films were heteroepitaxially grown on n-type Si substrates using pulsed laser deposition to construct TiN/Si heterojunction LPE devices.X-ray diffraction and high-resolution transmission electron microscopy analyses confirmed the excellent single-crystal quality and atomically smooth interface (surface roughness up to 0.35 nm) of the TiN films.Under 248 nm UV laser illumination, the heterojunction exhibited significant self-powered photoelectric response, with an open-circuit voltage peak of 79.3 mV (responsivity of 0.88 mV/mW) and ultrafast dynamic characteristics: a rise time of 17.7 ns and a relaxation time of 428 ns.In LPE testing, the device demonstrated position-dependent response, achieving a maximum sensitivity of 16.7 mV/mm (x < 4 mm region).The results indicate that the TiN/Si heterojunction significantly enhances the separation and diffusion efficiency of photogenerated carriers due to its high crystallinity and optimized interface structure, providing a new approach for developing high-performance self-powered UV position sensors.