Abstract: n order to create suitable nanoholes for quantum dot (QD) localization on InP and GaAs surfaces, we used atomic force microscopy in an intermittent contact mode coupled with a modulated voltage to realized local anodization at a nanometer scale. This method leads, after a few tens of milliseconds of oxidation, to an oxide height saturation and a low lateral growth rate for both surfaces. These specific results were used to control separately both the depth and the diameter of holes and to obtain compatible pattern for QD growth. We also demonstrated the thermal stability of these patterns at compatible temperatures with the InAs QD growth. First, results of QD growth on these patterns are presented.
Abstract: Low density InAs/InP(001) quantum dots, formed by the ripening of self-organized quantum sticks, are subjected to optical spectroscopy by photoluminescence and micro-photoluminescence. The presence of neutral multi-exciton states in single quantum dots is observed up to the 4X state. The large energy spacing between the s- and p-shells (90 meV) reveals the strong spatial confinement of carriers in such InAs/InP quantum dots. Micro-photoluminescence studies show that some dots are charged which allows us to measure the exchange energies in the InAs/InP quantum dots.
Abstract: In order to fabricate nanoscale oxide patterns on an InP(001) surface, local anodization by atomic force microscopy (AFM) contact and intermittent contact modes has been performed. Contact mode results are similar to those obtained with the local anodization of silicon, and mainly limited by the effect of space charge that occurs during the oxide growth. The existence of this space charge associated with the poor dielectric quality of the obtained oxide has been verified by performing scanning capacitance microscopy (SCM) measurements. Results for oxidation using intermittent AFM contact mode associated with a modulated voltage are more specific. For a more than two decade variation of probe velocity (0.01-5 um s[?]1), the AFM oxidation introduces no significant changes in the oxide pattern. Experiments on the influence of oxidation time give rise to two regimes. First, for times shorter than 100 ms, a high growth rate is found. Second, for oxidation times longer than 100 ms, we observe an oxide height saturation and a significant decrease of lateral growth rate. These results provide a way to easily control the oxide shape. The space charge neutralization in this mode has also been investigated by SCM. The interesting results for intermittent contact oxidation confirm the capability of this technique to modify a nanoscale InP surface.
