Abstract
The results of the research and design of a novel vacuum photosensor with a planar molybdenum blade structure are presented. The advanced prototype implements the principle of an increasing penetrability of the Schottky barrier for the metal–vacuum interfaces under the action of an external strong electrostatic field. 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. This causes features in the spectrum of the quantum yield of the photosensor such as expressed non-monotonic behavior and occurrence of sharp dips. The design of the photosensor that provides matching of the positions for both types of localization zones was proposed; the manufactured prototypes of the designed device were experimentally studied. 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.
Highlights
It is hard to overestimate the importance of high-performance photosensing devices and technologies for modern technical progress [1]
The structures based on ultrathin layers of semiconductors such as transition metal dichalcogenides with a fundamental absorption in the near infrared (NIR) and visible regions possess very favorable properties for successful applications in photonics and optoelectronics [8]
Measurement results in Figure 8a, performed at various levels of the gate potential, shows that an Analysis of the measurement results in Figure 8a, performed at various levels of the gate potential, increase in the electrostatic field strength leads to a noticeable increase in the photon emission with the shows that an increase in the electrostatic field strength leads to a noticeable increase in the photon wavelength ranging between 520–580 nm
Summary
It is hard to overestimate the importance of high-performance photosensing devices and technologies for modern technical progress [1]. Any photosensing device converts the incoming light to an electrical signal on the basis of photon absorption by a photosensitive material, with conversion of an optical into an electric signal realized Important applications of such units as high-speed information transceivers and communication networks [2,3], various types of remote sensing using the photosensitive matrices [4], and ultrafast sources of hot electrons in vacuum microelectronics devices [5,6] should be mentioned. The nanoscaled 2D layered structures based on the black phosphorus [9] opened up new possibilities for the bandgap control This ensures the photosensing tuning within a broad wavelength range (from the visible to the infrared). That all the mentioned photosensors are based on the internal photoelectric effect
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