Substrate removal for improved performance of QWIP-LED devices grown on GaAs substrates

Pixelless infrared imaging can be accomplished by epitaxially integrating a light emitting diode (LED) with a quantum well infrared photodetector (QWI P) large area device. The device acts as an infrared image converter by det ecting a mid-to-far infrared (M/FIR) signal using the QWIP and outputting a near-infrared (NIR) signal via the integrated LED. By removing the device substrate, the detector performance can be significantly improved. This pap er describes a substrate removal process, which uses a combination of mecha nical polishing and chemical selective wet-etch. The choice of a suitable o ptical adhesive and the control of carrier/device parallelism are the two m ost important factors determining the success of the process. (C) 2000 Else vier Science B.V. All rights reserved.