International Business Machines Corporation

Willi Walter

Heinz P Meier

Edward A Van Gieson

The process is particularly useful in the fabrication of GaAs quantum well (QW) laser diodes. Starting point is a ridge-patterned (100)-substrate (21), the crystal orientation of the sidewalls, e.g., (411A)-oriented, being different from that of the horizontal top. The sidewall facets thus have a lower Ga incorporation rate. In a molecular beam epitaxy (MBE) system, the lower AlGaAs cladding layer (22) is first grown, followed by the high-temperature growth of the active GaAs QW (23). Due to diffusion and desorption processes, the GaAs thickness at the sidewalls is smaller than on the horizontal top of the ridge. During a short growth interrupt, the GaAs completely desorbs from the sidewall facets. With the subsequent growth of the upper cladding layer (24), the QW becomes laterally embedded in higher bandgap material providing for lateral electric confinement.

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Adliswil, Switzerland

Willi Walter