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A method for the characterisation of the process-induced optical loss in butt-coupled passive waveguides will be described. In principle the results are valid for any active-passive waveguide butt-coupling as well (e.g. laser-waveguide). The method was applied to butt-coupled waveguides, which were grown by selective area metal organic vapour phase epitaxy (MOVPE). Different etching procedures for the preparation of the masked mesa stripes were examined, which considerably influenced the regrowth behaviour close to the mesa edge. The optical loss at the interface was found to depend primarily on the thickness difference of the waveguides. The excess layer thickness due the regrowth near the mesa is proportional to the width of the masked stripe. It reaches a factor of 1.7 at 50 μm wide stripes and decreases exponentially with distance from the stripe ( 1 e length = 26 μ m ). In general the measured loss values agree with the numerical simulation at least for stripe widths ≥30 μm. For stripe widths of ≤30 μm loss values ≤1 dB have been obtained in all cases, but deviations of the calculated loss values occurred, which can be attributed to the regrowth geometry at the interface.

This investigation reports on the overgrowth of GaInAs(P)/InP heterostructures on ridges having sidewall angles between 44° and 86°. The ridges were aligned towards the and 1 > direction. The most ideal tracking according to the step was found for the steepest etched angles with steps directed towards . The growth behavior on such a facet should allow for a high quality butt joint contact of two heterostructures devices. The growth in the perpendicular direction exhibits a different behavior as corrugations are observed in the step area. It seems that the different chemical reactivities of the various steps are responsible for the anisotropic growth behavior.

We report on the growth of highly uniform GaInAsP layers which can be achieved reproducibly over a long period. Quaternary layers with, e.g., λ g =1.050 μ m are obtained with a variation of the gap wavelength within ±1 nm over one wafer. For the run to run reproducibility nearly the same narrow tolerance band was measured. The effect of the substrate misorientation is briefly discussed. Finally we present the data of the fully MOMBE grown structure for the vertical integration of waveguides and photodiodes. Dark currents vary between 130–600 pA and the device capacity is below 100 fF for 10 V reverse voltage for the selected device geometry.

It has been shown that with Ga or As doped InP epitaxial layers exhibit improved material quality [H. Beneking et al., Appl. Phys. Letters 47 (1985) 828]. By proper choice of the doping content a reduction of dislocations as well as a minority carrier diffusion length enhancement are achievable [H. Beneking and N. Emeis, IEEE Electron Device Letters EDL-7 (1986) 98]. It is demonstrated that the application of this technique allows one to fabricate bipolar diodes with improved electrical characteristics. The application of the strained layer growth in conventional device processing steps as dopant indiffusion and multilayer epitaxial growth is demonstrated. Furthermore, the uniformity of the parameters is greatly enhanced, which will be shown by presenting data on the standard deviation of reverse currents on 1 cm 2 wafers.