光热电效应的机理、表征与性能综述

Mechanism,Characterization,and Device Application of Photothermoelectric Effect

光热电效应是近年来涌现的一种新型的光电探测机制,具有可零偏压工作、宽谱响应、不受带隙限制的优点,在红外和太赫兹波段具有广阔的应用前景。随着纳米材料中热载流子的高效利用以及对室温长波探测需求的增加,光热电效应研究近年来发展迅速,涌现出一系列新材料和新型器件设计方法。在近年来已发表的光热电效应综述文章的基础上,本文重点对光热电效应的机理、仿真、材料相关参数测量方法、器件设计,以及探测性能近三年的进展进行了梳理和总结,希望能给相关领域的研究人员提供有益参考。

Significance Photodetection is essential for obtaining optical information and computation.Photothermal and photoelectric detectors are two types of detectors that are widely used because of their different utilization advantages.The advantages of photothermal detectors include their broad spectral response and the ability to function at room temperature.The disadvantages of photothermal detectors include their relatively low detection speed and efficiency compared to photoelectric detectors.Photoelectric detectors exhibit high sensitivity and rapid response,but their material bandgap limits the detectable wavelength and typically requires operation under cryogenic conditions for small photon energy.The key scientific and technological demand is to overcome the bandgap limitation of materials and achieve room-temperature light detection in mid-and far-infrared and even terahertz bands.Therefore,investigations of related materials,mechanisms,and device design principles are urgent.The photothermoelectric effect is a photoelectric detection mechanism that uses the thermal effect generated by light and combines the thermoelectric response properties of materials to generate electrical signals.It has the advantages of zero external-bias operation,broadband optical response,and no bandgap limitation.Thus,the photothermoelectric effect has potential applications in infrared and terahertz photodetection.With the potential impact on the efficient utilization of hot carriers in nanomaterials and the demand for long-wave detection at room temperature,research on the photothermoelectric effect has rapidly advanced in recent years,with new materials and novel device designs emerging in this field.However,the mechanism,simulation,measurement methods of relevant material parameters,design guidelines,and detection performance of photodetectors based on the photothermoelectric effect still urgently need to be clarified and summarized in this field to deepen our understanding and enrich research tools.Progress Starting from the physical mechanism of the photothermoelectric effect,we systematically examined the factors influencing the photothermoelectric effect,such as the Seebeck coefficient,carrier mobility,optical absorption efficiency,and thermal properties.We reviewed the conductivity and Seebeck coefficient improvement method by adjusting the bandgap and effective mass of the carrier density of states through energy band engineering.We presented a theoretical formula and experimental method for optimizing the thermoelectric figure of merit by regulating the material selection,nanostructures,phonon spectrum,and thermal conductivity.The physical mechanism of the photogenerated carrier process was also discussed.We presented experimental differentiation methods for the photothermoelectric and photovoltaic effects(Fig.2),clarifying the different electromotive forces and photocurrent origins.We introduced a detailed multiphysical simulation model of the photothermoelectric effect using COMSOL finite-element simulation software and discussed the critical parameters for improving the photothermoelectric response.We summarized the experimental methods for measuring the material conductivity,Seebeck coefficient,thermal conductivity,thermoelectric merit,bandgap,carrier mobility,concentration,effective mass,and carrier scattering mechanism.We reviewed the research progress in photodetectors under the photothermoelectric effect in the past three years,particularly in one-dimensional carbon nanotubes,Ⅲ-Ⅴsemiconductor nanowires,two-dimensional materials,and materials with phonon-polariton characteristics.The performance of the photodetectors based on the photothermoelectric effect is summarized in Table 1.We introduced the optical,electrical,and thermal design guidelines,critical performance parameters,and recent applications of photothermoelectric effect photodetectors.Conclusions and Prospects Photothermoelectric effect photodetectors exhibit advantages of broadband optical response,nonexternal bias,and room-temperature operating conditions.Thus,they have promising applications in the visible,infrared,and terahertz photodetector regions.The photothermoelectric effect can also be applied to photovoltaics,material characterization,spintronics,and valleytronics.Before the bright application prospect,several vital problems remain to be solved for the photothermoelectric effect,such as the response speed,synergy effect of the photothermoelectric/photovoltaic effect,and optimization of thermoelectric materials with high carrier mobility.With continual research efforts in photothermoelectric effect photodetectors,extended applications based on the photothermoelectric effect are expected.