摘要
A figure of merit （FOM） Z = Up/τr, where Up is thepeak voltage, and τr is the rise time of the laser-induced thermoelectric voltage （LITV） signal, is defined for photodetector based on the LITV and the influence of the parameters on FOM is analysed based on the time dependence of LITVs in La1-xCaxMnO3 （LCMO） and YBa2Cu3O7-σ （YBCO） thin films grown on vicinal-cut substrates. We find that the FOM increases as the photon penetration depth decreases, and linearly increases with the thermal diffusion constant D. To achieve the highest FOM, the film thickness d has to be controlled to an optimum value. We also find that the FOM is directly proportional to the laser absorption coefficient no, the laser energy density per pulse E, the illuminated length of film 1, sin（2α） [αis the vicinal-cut angle], the Seebeck coefficient anisotropy （ Sab - Sc）, and is inversely proportional to the mass density ρ and the specific heat c0.
A figure of merit （FOM） Z = Up/τr, where Up is thepeak voltage, and τr is the rise time of the laser-induced thermoelectric voltage （LITV） signal, is defined for photodetector based on the LITV and the influence of the parameters on FOM is analysed based on the time dependence of LITVs in La1-xCaxMnO3 （LCMO） and YBa2Cu3O7-σ （YBCO） thin films grown on vicinal-cut substrates. We find that the FOM increases as the photon penetration depth decreases, and linearly increases with the thermal diffusion constant D. To achieve the highest FOM, the film thickness d has to be controlled to an optimum value. We also find that the FOM is directly proportional to the laser absorption coefficient no, the laser energy density per pulse E, the illuminated length of film 1, sin（2α） [αis the vicinal-cut angle], the Seebeck coefficient anisotropy （ Sab - Sc）, and is inversely proportional to the mass density ρ and the specific heat c0.
基金
Supported by the National Natural Science Foundation of China under Grant No 10274026, and a 2000/2001 Direct Grant under Project Code 2060204 of The Chinese University of Hong Kong.
