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

摘要

Pixelless infrared imaging can be accomplished by epitaxially integrating a light emitting diode (LED) with a quantum well infrared photodetector (QWIP) large area device. The device acts as an infrared image converter by detecting 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 paper describes a substrate removal process, which uses a combination of mechanical polishing and chemical selective wet-etch. The choice of a suitable optical adhesive and the control of carrier/device parallelism are the two most important factors determining the success of the process.