Partial-electroded ZnO pyroelectric sensors for responsivity improvement

Electrode layout of ZnO pyroelectric sensors

“…A pyroelectric device, with a partially covered electrode, has excellent output signals due to the pyroelectric film being directly exposed to incident radiation [4]. Therefore, the electrode layout plays an important role in the temperature variation rate of pyroelectric films and the responsivity of pyroelectric devices.…”

“…This has been analyzed by a two-dimensional finite element model, with various film dimensions and material properties [9]. The partially covered electrode has better output signals than the fully covered electrode [4]. In the present study, a two-dimensional finite element model is generated by commercial multiphysics software COMSOL MULTIPHYSICS ® 3.5 to explore the temperature variation rate in the ZnO pyroelectric sensors with both partially covered and fully covered electrodes.…”

“…In other words, a higher temperature variation rate in the ZnO layer leads to a higher response current for the pyroelectric sensor. A partially covered top electrode has a higher responsivity than a fully covered top electrode because the uncovered part of the ZnO layer is directly exposed to the heat source and thus markedly increases heat absorption [4]. The pyroelectric sensors, with partially covered and fully covered top electrodes, are fabricated by both surface and bulk micromachining on the silicon substrate, as shown in Fig.…”

“…A higher temperature variation rate in the pyroelectric layer leads to a higher response current for the pyroelectric sensors. A partially covered, top electrode has been proven to result in a higher responsivity than that of a fully covered electrode because it opens windows for the ZnO layer to directly come into contact with the heat source [4]. Therefore, the electrode layout plays an important role in pyroelectric sensors.…”

“…The most densely packed and thermodynamically favorable growth orientation in a ZnO wurtzite structure is the one with the c-axis perpendicular to a substrate. ZnO films, with the c-axis normal to the substrate, are preferred in many applications, such as ZnO pyroelectric devices [4,6] and film bulk acoustic resonators [7]. The pyroelectricity of ZnO is attributable to non-centro-symmetrical crystals and has a specific polar axis along the direction of spontaneous polarization [1,2].…”