What is it about?
Theoretical and experimental substantiation of the photosensor performance in a wide range of wavelengths (from 430 to 680 nm and from 800 to 1064 nm) beyond the threshold of the classical photoelectric effect is given. The finite element method was applied to calculate distribution of the optical and electrostatic fields inside the photosensor structure. The sensor current-to-light response was studied using the periodic pulsed irradiation with the tunable wavelength. It was shown that the nanoscale localization zones of two types are formed near the surface of the blade tip: the zone of an increased concentration of hot electrons localized inside the molybdenum blade, and the zone with an increased strength of the external electrostatic field localized outside the blade. In general, the mutual positions of these zones may not coincide, whereas the position of the first-type localization zone significantly varies with the changes in the wavelength of the irradiating light.
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Why is it important?
In the designed photosensor, the ballistic transport of photoelectrons in the vacuum gap with a strong field provides a possibility for the creation of ultra-fast optoelectronic devices, such as modulators, detectors, and generators.
Perspectives
Along with the broadband of the studied photosensor, it is necessary to note the following additional advantages in comparison with analogues:( i) The simplicity and low cost of manufacturing technology (traditional photolithography comparedwith e-beam lithography, molybdenum instead of gold). (ii)The “open” structure of the photosensor electrodes allows the formation of a directed electronflow from the tip of the blade into the free space. This is important for creating current sourcesfor vacuum devices (X-ray tubes, UHF (Ultra high frequency) and THz (Terahertz) generators,and amplifiers) with ultrafast optical signal modulation. In known analogues with nanoscalevacuum gap, the possibility of forming an electron flow with a controlled trajectory is associatedwith great difficulties
Professor Alexander N Yakunin
Institute of Precision Mechanics and Control
Read the Original
This page is a summary of: A Visible and Near-IR Tunnel Photosensor with a Nanoscale Metal Emitter: The Effect of Matching of Hot Electrons Localization Zones and a Strong Electrostatic Field, Applied Sciences, December 2019, MDPI AG,
DOI: 10.3390/app9245356.
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