Large format, broadband and multi-color GaAs/AlGaAs quantum well infrared photodetector (QWIP) focal plane arrays

The GaAs/AlGaAs based Quantum Well Infrared Photodetectors (QWIPs) afford greater flexibility than the usual extrinsically doped semiconductor IR detectors because the wavelength of the peak response and cutoff can be continuously tailored over any wavelength between 6-20 mum. The spectral band width of these detectors can be tuned from narrow (Deltalambda/lambda similar to 10 %) to wide (Deltalambda/lambda similar to 50 %) allowing various applications. Also, QWIP offers multi-color infrared cameras which is capable of simultaneously acquiring images in different infrared bands. Each pixel of such array consists of vertically stacked, independently readable, QWIP detectors sensitive in different narrow (Deltalambda similar to 1 mum) infrared bands. In this article, we discuss the results of a 10-16 mum large format broadband QWIP focal plane array (FPA). The size of the FPA is 640x512 and its pixel pitch is 25 microns. The highest operating temperature of the FPA is 45K, and it was determined by the charge storage capacity and the other features of the particular readout multiplexer used in this demonstration. Excellent imagery, with a noise equivalent differential temperature (NEDeltaT) of 55 mK has been achieved. In addition, we will discuss the developments and results of the 640x512 dual-band QWIP FPA.