Direct detection of electronic states for individual indium arsenide (InAs) quantum dots grown by molecular beam epitaxy

[Display omitted] •The dome-shaped Indium Arsenide (InAs) Quantum dots (QDs) are fabricated by using molecular beam epitaxy (MBE).•These individual QDs of heights 2–3 nm are observed using the AC mode topography of the atomic force microscope.•After identifying these well separated (∼150 nm) QDs on the surface, the electrical measurements are carried out by conducting mode of AFM.•During I-V measurement on these QDs, the lower turn-on voltage is observed compared to its initial sweep, confirming the confined electronic states in InAs QDs. Indium arsenide (InAs) quantum dots (QDs) have been characterized using a conductive-mode atomic force microscope (C-AFM), where a well-defined gold-coated AFM probe has been used to electrically probe each individual QD. The InAs QDs were grown on a gallium arsenide (GaAs) substrate in a self-assembled manner by using molecular beam epitaxy (MBE). The measured current-voltage (I-V) curves of individual QDs exhibit a typical Schottky diode behavior, which can be attributed to the metal/semiconductor junction between the AFM gold probe and the n-doped GaAs bulk. However, distinct I-V curves are observed in sequential measurements, where a less forward turn-on voltage is measured in the subsequent voltage sweeps compared to the initial sweep. However, this effect is not evident when the same measurements are conducted on a plane surface (in the absence of QDs) on the same substrate. The discrete voltage values at the forward bias on a QD indicates a change in the electronic states due to trapped electrons in the QD during the initial voltage sweep. These unique characteristics of QDs can be exploited for potential applications in fast-response data storage devices and quantum computing.