Growth of Nb2O5 quantum dots by physical vapor deposition

• Nb2O5 QDs grown by PVD are being reported for the first time in literature.
• This method gives the freedom of growing QDs on any substrate/surface.
• The band gap of dots scales with inverse square of dot size.
• Process of growing dots of desired size can be quite useful for many applications.
• Exitonic effective mass (µ=0.532) of Nb2O5 determined by this study for first time.

The crystalline quantum dots of Nb2O5 in the range 1–20 nm have been grown by vacuum thermal evaporation using the bottom-up approach of early nucleation and growth stage. The dot sizes were controlled by growth time for an optimized constant molecular flux rate of growth. The dots were characterized by TEM and UV/Vis absorption spectroscopy. The variation of optical band gap of dots scaling with inverse square of their size demonstrates the quantum confinement effect in the dots. The reduced mass of electron–hole pair (exciton) was determined to be 0.532 me from this behavior.