We report on the shape and polarization control of site-controlled multiple and single InAs quantum dots (QDs) on InP pyramids grown by selective-area metal-organic vapor phase epitaxy. With increasing growth temperature the QDs elongate causing strong linear polarization of the photoluminescence. With reduced pyramid base/pyramid top area/QD number, the degree of polarization decreases, attributed to the symmetric pyramid top, reaching zero for single QDs grown at lower temperature. This control of linear polarization is important for entangled photon sources operating in the 1.55 μm wavelength region.

Nötzel, R. (2009). Distribution control of 1.55 m InAs quantum dots down to small numbers on truncated InP pyramids grown by selective area metal organic vapor phase epitaxy.

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Chlorine-based inductively coupled plasma etching processes are investigated for the purpose of etching twodimensional photonic crystals in InP-based materials. Etch rates up to 3.7 m/min and selectivity's to the SiN mask up to 19 are reported. For the removal of indiumchloride etch products both the application of elevated temperatures and high ion energy's are investigated. The reactor pressure is an important parameter, as it determines the supply of reactive chlorine. It is shown, that N 2 passivates feature sidewalls during etching, improving the anisotropy. Ions that impact onto the sidewalls, either directly or after scattering with the SiN-mask or hole interior, cause sidewall etching. Highly directional ion bombardment and vertical sidewalls in the SiN-mask are therefore crucial for successful etching of fine high aspect ratio structures.