China has prepared high-detection, fast response speed, etc.

[ Instrument Network Instrument Development ] Recently, solid silver/titanium oxide Schottky diodes have made progress in the research of thermal electronic photodetectors. Related research results were published on Nanophotonics (Nanophotonics, 8(7), 1247-1254 (2019)).

Figure 1. The structure of the detector and the photoresponse process involved in the separation of thermionic electrons. (A) Schottky-type current-voltage curve of a hole array silver/titanium oxide composite film under vacuum. (B) SEM photograph of a silver/titanium oxide composite film. (C) Spectral response of the pore array silver/titanium oxide detector. (D) The energy band of the isothermal thermal electrons participating in the photocurrent response

Light can excite the plasma element on the surface of the metal, and the plasma element can further excite high-energy hot electrons. These hot electrons can form a current across the metal/semiconductor Schottky junction, thereby realizing the transition of light to electricity and achieving photoelectricity. probe. Thus, a new plasmon-coupled thermal photodetector composed of a metal/semiconductor Schottky junction has recently been developed. Compared with traditional semiconductor detectors, this detector has the special advantage that it can detect photons with energy less than the semiconductor band gap, and its response wavelength can be controlled and continuously adjusted by controlling the metal nanostructure. In recent years, most of the research on plasmon thermal electron photodetectors has focused on the improvement of the responsiveness of thermal electron detectors, and the lack of performance and detection speed, which are crucial in the field of photoimaging and optical communication. Research.

The silver/titanium oxide Schottky junction is considered to be an ideal thermal electron detector construction material. On the one hand, silver has a high isotropic local field and a narrow thermal electron energy distribution, which can produce high photoelectric conversion efficiency. On the other hand, titanium oxide has a high density of conduction band states, facilitating rapid transfer of electrons. Therefore, a thermal electron detector based on a silver/titanium oxide Schottky junction is expected to have a high detection rate and a fast response speed.

Solid state researchers prepared plasmon-based thermo-electronic photodetectors based on a hole array silver/titanium oxide Schottky junction (Fig. 1). The detector exhibits fast response speed and high detection rate. The light response rise and fall times are 112 μs and 24 μs at a wavelength of 450 nm and zero bias, respectively, and the detection rate is 9.8 × 1010 cmHz1. /2/W (Figure 2), both performance indicators are higher than previously reported in the literature. Further, they increased the optical responsivity of the device from 3.4 mA/W to 7.4 mA/W by lowering the Schottky barrier height. Related research provides reference and guidance for the development and performance improvement of plasmon thermal electron photodetectors.

This research work was supported by the National Natural Science Foundation of China and the CAS/SAFEA International Innovation Research Team.

(Original title: Isothermal electronic photodetectors with high detection rate and fast response speed prepared by solid state)