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Study on Impact of Photoreceptive Layer
Thickness on Performance of A-Gaox -Based Solar-Blind Ultraviolet
Photodetectors
CHANG Dingjun , LI Zeming , ZHANG Hezhi
Journal of Jilin University (Information Science Edition). 2024, 42 (3):
567-572.
Due to
its low background noise, solar-blind ultraviolet photodetection technology is
widely used in fields such as fire monitoring, missile detection, and military
communication. Compared to other solar-blind ultraviolet sensitive materials,
amorphous gallium oxide offers several advantages, including a bandgap that
matches the solar-blind ultraviolet region, structural stability, and good
mechanical strength. The horizontal metal-semiconductor-metal structured
photodetectors are known for their simple production processes, ease of
integration, and suitability for industrialization. Given the non-uniform
distribution of the internal electric field and the photo-generated carriers
along the thickness direction in horizontal devices, the thickness of the
photoreceptive layer plays a crucial role in the performance of the
photodetectors. In order to fabricate high- performance solar-blind ultraviolet
photodetectors, amorphous gallium oxide thin films were prepared using low-
temperature metal organic chemical vapor deposition method. Structural
characterization of the films confirmed their amorphous nature, and the film
surfaces were found to be relatively flat, with the optical absorption edge
located within the deep ultraviolet spectral range. Solar-blind ultraviolet
photodetectors were subsequently developed. As the thickness of the
photoreceptive layer increased from 33. 2 nm to 133. 6 nm, the dark-current of
the photodetector rose from 2. 33*10-10 A to 2. 12*10-8 A, and the photo-current
under 254 nm illumination increased from 1. 66 * 10-7 A to 3. 2 * 10-5 A.
Additionally, both the responsivity and the external quantum efficiency of the
photodetectors increased by orders of magnitude with the increase in the
photoreceptive layer thickness, reaching maximum values of 2. 91 A/ W and 1
419. 12% , respectively. The thickness-dependent characteristics of the
photodetectors can be attributed to the interfacial high-defect layers, light
absorption intensity, and the geometric parameters of the photodetectors. The
photodetectors exhibited excellent wavelength selectivity, the current of each
photo-detector under 365 nm illumination and the photo-current under 254 nm
illumination differ by more than two orders of magnitude. Moreover, over the
tested 5 cycles, the response / recovery behavior of each photodetector
consistently demonstrates good repeatability and stability.
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