Abstract
In this work, the nano-scaled mesh electrodes are fabricated by obliquely depositing metals through the highly ordered polystyrene nanosphere mask. Furthermore, the intrinsic MgZnO film is deposited as the absorption layer for the metal-semiconductor-metal ultraviolet photodetectors (MSM-UV-PDs) using the vapor cooling condensation system. The 100-nm-linewidth nanomesh electrodes with metal occupying a roughly 10% of the device surface region consequently render PDs with a high transmittance in the ultraviolet (UV) wavelength range. The photoresponsivity of MgZnO-based MSM-UV-PDs evaluated at the wavelength of 330 nm with the operating bias voltage of 5 V is elevated from 0.135 to 0.248 A/W when the thin metal electrode is replaced by the nanomesh electrode, and the corresponding quantum efficiency is improved from 50.75 to 93.23%. Finally, adopting the nanomesh electrode also helps to enhance the UV-visible rejection ratio (R330nm/R450nm) and the detectivity from 1663 and 1.78 × 1010 cmHz0.5W−1 to 2480 and 2.43 × 1010 cmHz0.5W−1, respectively.
Highlights
The ultraviolet photodetectors (UV-PDs) have been widely employed in inter-satellite communications, ozone monitoring, missile detection, flame sensor, and chemical/biological analyzer[1,2,3]
The nanosphere lithography technique and the oblique evaporation method have been used to fabricate the 100-nm-linewidth nanomesh electrodes patterned on the MgZnO-based MSM-UV-PDs, because the oblique evaporation has the larger nanosphere cast shadows than that of the conventional vertical evaporation
The thin metal electrodes are fabricated on the MgZnO-based MSM-UV-PDs using the same fabrication processes for comparison
Summary
The ultraviolet photodetectors (UV-PDs) have been widely employed in inter-satellite communications, ozone monitoring, missile detection, flame sensor, and chemical/biological analyzer[1,2,3]. With the exception of the metal oxide transparent conductive films, the thin metal electrodes are often utilized as the illuminated electrode on the MSM-UV-PDs6,7. Their relatively low transmittance in the UV wavelength range further prevents PDs from gaining additional improvement. To address the above-mentioned issue, the nanomesh electrode fabricated by the solution-processed metal nanowires proposed in previous reports is a good solution to enhance the optical and electrical properties of the UV-PDs and the other optoelectronic devices[9,10]. The nanomesh electrode with the random metal nanowire distribution leads to the simultaneously decrease in the optical and electrical properties of the applied optoelectronic devices. The optical and electrical characteristics of MSM-UV-PDs with nanomesh electrodes of various sizes are subsequently investigated in this work
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