InAs dots grown on InP (001) by droplet hetero-epitaxy using OMVPE

We have successfully obtained InAs dots on InP (001) by droplet hetero-epitaxy and observed room-temperature photoluminescence (PL) spectrum with a peak at around 1.6 μm. Dependences of the surface morphology on the substrate temperature and on the trimethylindium (TMIn)-supply time were investigated. From atomic force microscopy (AFM), images of the samples prepared by varying the TMIn-supply time, a critical coverage for supplied In to form droplets was found to exist between 1.5 monolayers (MLs) and 3 MLs. This result was confirmed by low-temperature PL measurements. At the TMIn-supply of 3 MLs, which was above the critical coverage, small dots of height ≈5 nm were formed with the density of 9.8x109 cm−2. A PL spectrum of the sample grown using the same sequence followed by the growth of a 10 nm InP cap-layer, exhibited a 1.6 μm emission, with a full width at half maximum (FWHM) of 150 meV at room temperature.