Integrated quantum well intersubband photodetector and light-emitting diode for thermal imaging

Thermal imaging devices -- especially large two-dimensional focal plane arrays -- are useful for a wide rage of applications. A key factor that has limited thermal imaging mainly to military applications is the cost of the imaging system. The approach taken here to overcome the cost limitation involves the integration of a quantum well intersubband photodetector (QWIP) and a light emitting diode (LED) for making large two-dimensional focal plane arrays. The advantage of this unique new approach over the conventional one is that it uses a mature GaAs-based materials system and avoids hybrid bonding with Si multiplexer chips. A demonstration device has been made and is discussed here, with the QWIP operating at a peak detection wavelength of 9 micrometer and the LED emitting at 930 nm. The performance issues are also addressed.