Time dependence of laser-induced thermoelectric voltages in La1−xCaxMnO3 and YBa2Cu3O7−δ thin films

Abstract

The time dependence of laser-induced thermoelectric voltage (LITV) in La1−xCaxMnO3 (LCMO) or YBa2Cu3O7−δ (YBCO) thin films grown on a vicinal SrTiO3 substrate is derived. From the fitted curve of the measured time evolution of the LITV, several parameters of a LCMO thin film are deduced.

Doping dependence of laser-induced transverse thermoelectric voltages in the perovskite Nd2−x Ce x CuO4 thin films

“…The voltage signals are believed to arise from the off-diagonal term of the Seebeck tensor along the thin film surface, which is present in the anisotropic layered materials when an inclined crystal orientation is constructed [2,3]. This laser-induced thermoelectric voltage (LITV) effect has the specifics that a temperature gradient applied along the film normal direction gives rise to a transverse voltage signals along the film in-plane direction [4][5][6][7] and has been applied in the light-detection devices with advantages of fast time and broad spectral response, operating at room temperature but no bias required [8][9][10].…”

“…According to the atomic layer thermopile (ALT) model, huge enhancement to LITVs originates from numerous series junctions between different atomic layers epitaxially grown along the steps of the vicinal-cut substrate in microscale [2,5]. These tilted thin films are referred to ALT materials, and the LITV response can be optimized by tailoring the film thickness and the inclined crystal orientation [6,7,11].…”

“…These tilted thin films are referred to ALT materials, and the LITV response can be optimized by tailoring the film thickness and the inclined crystal orientation [6,7,11]. LITV signals have been detected in several cuprates [4][5][6][7][8][9][10][11][12][13][14][15] which are correlated with the perovskites of Ruddlesden-Popper family [16], since the layered structures can cause different transport properties in various atomic layers and then large anisotropic thermopower DS, a key factor to LITV effect [2,5]. LITV signals are observed scaling to the resistance of thin films [17], and the doping dependence always shows the same behaviors as the change in DS upon the charge carrier density [14,15].…”

Broadband Photodetectors Based on c-Axis Tilted Layered Cobalt Oxide Thin Films

“…seebeck coefficient in the ab-plane and along the c-axis of the film, realizing ∆S =S ab −S c of tens of V/K, which is about several times larger than that of YBCO (~ 10 V/K) and hundreds times larger than that of LCMO (~ 0.22 V/K ) [3,4]. This fact indicates the layered cobalt oxides might have potential applications in the field of high-sensitive broadband photodetectors.…”

“…Laser-induced voltage (LIV) effects in c-axis tilted thin films of YBa 2 Cu 3 O 7- (YBCO) and La 1-x Ca x MnO 3 (LCMO) have been extensively studied in the past decades due to their potential applications in photodetectors [1][2][3][4][5][6][7][8][9]. Compared to the commonly used photodiodes-based photodetectors, this new type of photodetectors has the advantage of broad spectrum response ranging from ultra-violet (UV) to infrared (IR).…”