Effects of the Substrate on the Response of P(VDF-TrFE) Pyroelectric Detector

Abstract

The thermal analysis on the response of pyroelectric detector revealed that an optimal configuration structure could be found for a certain frequency range. Thus, it appeared that the pyroelectric layer should be thick at low frequencies but it should be very thin at high frequencies. The introduction of a thermal insulator is done trying to find out a trade off between sensitivity and response time. It has been found that its influence is restricted to a certain frequency range. The optimal thickness is related to the thermal diffusion length. We noticed also that it depends very little on the configuration structure.

Extrinsic size effect of pyroelectric response of ferroelectric films

“…The overall view and features of the curve 2 in Figure 3c are similar to those calculated by Mahrane et al [29] and Simonne et al [30] for P(VDF-TrFE)-on-Si structure (see Fig. 2 in these papers).…”

“…Schopf et al [28] revealed the weak dependence of h opt on the substrate thickness under the practical equality of h opt and λ T . The dependence of h opt on ω (and so on λ T value) was also pointed out by Mahrane et al [29]. Thus the existence of the optimal relationships between thermal and geometric parameters of the pyroactive layer, substrate and modulation frequency necessary to achieve the maximal value of pyroelectric response are very likely.…”

“…The addition of intermediate thermal isolating layer was proposed for thermal decoupling of the film and substrate [28][29][30]38], and the effectiveness of the air gap was also considered [44,45]. With the same purpose integrated structures with PVDF/TrFE copolymer [30,32] and with SiO -aerogel 2 [41][42][43] thermal isolating layer were studied and then fabricated.…”

“…by increasing ω (a T is the diffusivity of the media, where the temperature wave propagates). Therefore the question about the optimal configuration of the film-on-substrate type structure for operation at a given frequency (or in the certain frequency range) was raised and considered [22,23,28,29].…”

“…The influence of the substrate thickness and relative effusivities of pyroelectric layer and substrate on pyroelectric response has been considered [23]. Also the influence of the thickness of substrate and its thermal parameters [23,25,38], or thermal quality of substrate [24], or the thickness of pyroelectric layer [29] on pyroelectric response was considered. To the best of our knowledge the optimal relationship has not been established yet, and that is why we decided to consider the problem in this work.…”