Junko Asayama

Pyroelectric infrared array sensors made of c-axis-oriented La-modified PbTiO3 thin films

Highly sensitive pyroelectric infrared sensors (linear array and two-dimensional array) have been fabricated by using highly c-axis-oriented La-modified PbTiO3 (PLT) thin films, together with a new process and new sensor structures. The PLT thin films were deposited by RF magnetron sputtering. The films have a high pyroelectric coefficient γ of 6.5 × 10−8 C/cm2 K and a high figure of merit for specific detectivity D* without a poling treatment. Two types of linear array sensors, reticulated and non-reticulated ones, have been fabricated. The reticulated and non-reticulated sensors have 64 elements with 0.2 mm pitch and 128 elements with 0.1 mm pitch, respectively. A remarkably high D* value of 5 × 108 cm Hz 12/W and a very low crosstalk of < 3% at 100 Hz have been attained. The linear array and discrete JFET chips are incorporated within a pin-grid package. A high performance two-dimensional sensor with 32 × 32 elements based on a new method of reading-out signals can be formed. An array sensor with a new device structure has been designed by using an optical scanning slit. On the infrared system with F = 1 optics and Δf = 20 Hz filter, a noise equivalent temperature of 0.2 K has been obtained.