Optical characterisation of strained-layer InxGa1-xAs/GaAs MQW LED grown by MOVPE

We present the use of photoreflectance (PR) spectroscopy combined with the standard photoluminescence (PL) and electroluminescence (EL) for the room temperature optical investigation of strained-layer multiple quantum well (MQW) InxGa1-xAs/GaAs light emitting diode (LED) for 1040 nm. In the PR spectra, except the fundamental transition observed also in the emission spectra, two extra features related to the active region of the device have been seen. The presence of these two excited state transitions allowed the band structure to be analysed and the correctness of the device performance to be checked. We repeated the measurements after the top p-doped GaAs cladding layer had been etched oh and discussed the changes of the built-in electric field.