Cathodoluminescence Study of InP Photonic Structures Fabricated by Dry Etching

Abstract

International audienceRidge waveguides fabricated by inductively coupled plasma (ICP) etching using chlorine-based gases were studied by spectrum image cathodoluminescence (CL). Structures with different dimensions (height and width) were studied, evidencing the generation of defects during ICP processing. Using the CL spectrum images, the distribution of the stresses induced by the defects was mapped. The residual stresses depend on the dimensions of the waveguides. Using finite-element analysis the strain distribution was reproduced. The initial strain conditions provided a picture of the distribution of the defects generated by the etching process, showing differences between the etched floor, the side-walls of the waveguides, and the unetched top surface. The possible mechanisms for defect formation, as well as the possible identity of the defects, are discussed

Mechanical stress in InP and GaAs ridges formed by reactive ion etching

“…The apparent discontinuity at the ridge edges is not an artefact. It arises from the fact that the scanned region inside the ridge lies near the top surface, whereas it lies near the bottom etched surface outside the ridge 25 . The etch depth (3 µm) is much larger than the depth probed in InP by the 5 kV electron beam in the CL measurement.…”

Polarized cathodoluminescence for strain measurement

“…Strain in light emitting semiconductors can also be assessed using photoluminescence (PL) 6,14 or cathodoluminescence (CL) [15][16][17][18][19][20] spectroscopy. In these techniques, the hydrostatic component of the deformation is given by the spectral shift due to electronic transitions through the material's bandgap.…”

“…20 The strain fields induced by the HM are well known and have been modelized. 20 Etched InP samples have also been characterized by CL spectroscopy 18,19 and DOP of PL 19 although in the top view only. Etching is suspected to introduce stress within the patterned lines.…”

Evidence of chlorine ion penetration in InP/InAsP quantum well structures during dry etching processes and effects of induced-defects on the electronic and structural behaviour

“…Berrier et al [1] studied the effect of dry etching conditions on carrier lifetime reduction in InAsGaP quantum wells (QWs) in InP-based photonic crystal structures. In early studies, using cathodo-luminescence (CL) spectral imaging, we have looked at the effects of dry etching on the spectroscopic properties of rectangular ridge waveguides etched in InP or QW structures on InP ( [2,3]). It was shown that mechanical stress is induced in such structures following the dry etching.…”