A 256-pixel pyroelectric linear array with new black coating

This paper gives a survey of both the design and essential properties of newly developed pyroelectric linear arrays made on the basis of lithium tantalate (LiTaO₃). There are up to 256 pixels with a minimum pitch of 50 μm. The detector is a hybrid arrangement of pyroelectric detector chip and 0.8 μm CMOS read-out circuit in a hermetic metal housing. Thanks to the development of a new black coating technology the thermal resolution and the homogeneity of the spectral responsivity have been permanently improved. The absorption layer consists of a columnar NiCr thin film. It is deposited using a special GLAD technology in high vacuum. The band absorption coefficient in the wavelength range 1...15 μm is about 0.9 for a layer with a thickness of about 1 μm. The NiCr absorption layer has very low thermal mass and high temperature stability. It can be patterned by lift-off technology. The measurement results demonstrate the excellent homogeneity of the spectral responsivity and the improvement of the signal-to-noise ratio of the linear arrays.