Abstract: 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.

Abstract: Modulation of a semiconductor laser device is achieved at microwave frequencies by the application of transverse fields which produce energy shifts in the gain spectra of the laser device. The laser device is a PN diode which has a body portion constructed from a nonconductive material, with P and N type implants on opposite sides. The P and N implants define a transition region, or layer, on the order of 1 micron in width, in which is formed a quantum well having a thickness on the order of 50 to 100 Angstroms. Application of a bias voltage across the PN junction provides lasing of the device. An electrode on the surface of the transition layer allows application of a transverse electric field to the PN junction. This transverse field quenches the lasing of the device, to provide modulation of the laser.