PYRAMIDAL QUANTUM-DOT STRUCTURES BY SELF-LIMITED SELECTIVE-AREA METALORGANIC VAPOR-PHASE EPITAXY

We have fabricated AlGaAs/GaAs quantum dot structures using selective area metalorganic vapor phase epitaxy (MOVPE). First, GaAs pyramidal s tructures with four-fold symmetric {011} facet side walls are formed o n SINx masked (001) GaAs with square openings. After the pyramidal str uctures were completely formed, no growth occurs on the top or side wa lls of the pyramids. Furthermore, the shape and width of the top area observed by a scanning electron microscope (SEM) and an atomic force m icroscope (AFM) is shown to be highly uniform. This indicates that sel f-limited growth occurs. Next, using these uniform pyramids, GaAs quan tum dots are overgrown on top of the pyramids using different growth c onditions. Sharp photoluminescence (PL) spectra are observed from unif orm quantum dots.