Wide bandgap film laser detection element

Abstract

The invention provides a wide bandgap film laser detection element. The laser detection element comprises an Al<1-x>GaxN gradient film, and is characterized in that the Al<1-x>GaxN gradient film is used as a photo-thermal sensitive layer. Compared with the prior art, the wide bandgap film laser detection element has the beneficial effects that (1) the wide bandgap film laser detection element gives consideration to the responsivity of a surface sensitive layer and the high thermal conductivity of a film / substrate interface, the energy density is high, and high-power laser detection does not need refrigeration; (2) the wide bandgap film laser detection element is wide in short wave detection limit range and good in linearity; and (3) the wide bandgap film laser detection element is suitablefor large-scale production.

Description

technical field [0001] The invention relates to a wide-bandgap thin-film laser detection element, which belongs to the field of functional thin-film materials and devices. Background technique [0002] The thin-film photothermal detection device based on the off-diagonal element Seebeck effect, through the tilt design of the film epitaxial orientation, makes the off-diagonal elements of the material Seebeck coefficient tensor not zero, so that the response electric field and the direction of the temperature gradient are perpendicular to each other. The relative independence of thermal and electrical transport dimensions enables real and sensitive photo-thermal-electrical response signals to be obtained in a nanoscale single-layer film, and also includes multiple physical mechanisms such as photoconductivity and lateral Dandelion effects. Compared with the traditional photonic laser detector, it has the advantages of simple structure, no power drive, wide response spectrum, d...

AI Technical Summary

Problems solved by technology

[0003] However, the sensitive materials currently used for such devices are mainly layered oxides and their multilayer films / superlattices, such as (Ca / Na) x CoO 2 , YBa 2 Cu 3 o 7-δ , La 1-x Ca x MnO 3 , La 1-x Sr x CoO 3 etc., are high-melting point multi-element metal oxide films, and their high quality c Axis-tilt epitaxial growth relies on pulsed laser deposition (Pulsed Laser Deposition, PLD), which limits mass production

In addition, this type of system thin film and its matching single crystal substrate such as SrTiO 3 , LaAlO 3 , (La 1-x Sr x )(Al 1-y Ta y )O 3 The thermal conductivity at room temperature is less than 10 W / m·K. Although the low thermal conductivity makes the temperature gradient established under the unit heat flux larger and the transverse voltage responsivity higher, it also makes the detection element work under high-power continuous light. It is difficult to transmit heat to the metal heat sink in time under irradiation, resulting in a continuous decrease in the temperature gradient between the upper and lower surfaces of the film, a continuous decline in the responsivity, and a decrease in detection sensitivity, time resolution, repeatability, and damage threshold

[0004] In addition, due to the narrow bandgap width of the existing detection element materials, such as the commercially available YBa 2 Cu 3 o 7-δ , Ca x CoO 2 The optical bandgap of the system is about 1.0 eV at room temperature. When the irradiated photon energy is greater than the bandgap, multi-effect recombination such as photoconductivity will provide additional carrier concentration and improve the response speed of the device, while electronic transitions in the valence band will also affect The responsivity of the device makes the normalized responsivity change significantly under different wavelengths of irradiation, resulting in poor linearity of the device, and the actual usable detection wavelength range is narrow

[0005] In summary, due to the limitations of the current material system and manufacturing process, thin-film laser detection elements based on the off-diagonal element Seebeck effect have problems such as difficulty in mass production, poor heat dissipation performance, and low linearity in wide-spectrum detection.

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