Effects of selective wet etching on the spectral properties of a vertical-cavity surface-emitting laser/detector

In this paper, we present results on modelling, fabrication and characterization of oxide-confined VCSELs for short-distance alternative emission and photodetection at 820 nm. In the present designed single-cavity GaAs-based device, the buried oxide layer is not only used to obtain a single mode laser beam but also to enable decoupling between a small surface emission, limited by the aperture and a large surface detection, limited by the internal diameter of the top electrodes. The selective wet etching was found to improve simultaneously the detection sensitivity and the differential quantum efficiency without damaging the active surface.