Tunable Near Infra Red InP / InGaAs QWs Based Photodetector Integrated in a MOEMS Structure for the Realisation of a Micro-Spectrometer

This paper deals with the design and realisation of a Near Infra-Red (NIR) micro-spectrometer (1.5 to 2 mum) for non invasive detection. The device is based on an InGaAs strained QWs photodiode integrated in a MOEMS structure for wavelength tunability. We address two main challenges which are the realisation of a long wavelength photodetector combined with the fabrication of a micro-machined tunable air-gap cavity resonator. We present first the design and process critical issues related to the residual strain management in the structure. The InGaAs QW growth aspects are presented. We also describe an example of a system for the monitoring of the sugar concentration in water which has been chosen to validate the concept.