Epitaxy of quantum dash structures on InP and their application in telecommunication lasers

In this work the fabrication and characterisation of low-dimensional structures that can be used as active regions in InP semiconductor lasers are presented. The presented structures were grown in a gas source molecular beam epitaxy system. The formation of the quantum dot-like structures was also optimised in test samples. Some of the dash properties shown for test structures were also demonstrated for laser structures. By varying the thickness of the dash layers from 5 to 7.5 MLs a shift of the emission wavelength of about 230 nm was realised bearing potential for an even further extension of this method. Also a stack of six dash layers all slightly different in thickness was embedded in a laser structure. Using subthreshold spectra a gain width of 220 nm was measured giving the opportunity to cover the whole telecommunication band with a single device. Also some ridge waveguide lasers were processed and analysed. These lasers show promising results with high maximum output powers of up to 15 mW per facet and low threshold currents. Especially a 300 μm long device with coated facets exhibited a very good threshold current of 20 mA at room temperature and a maximum operation temperature of 60 C under cw operation. In pulsed mode this laser could be operated up to 130 C. (orig.)