Semiconductor nanostructures

The optical properties of semiconductor quantum dots (QDs), such as broad absorption band and size dependent spectral emission, together with the high effective surface area available for interaction with target chemicals are attractive for applications like chem-/bio-sensors and lab-on-chips. QDs emitting in the near-infrared (NIR) range, in particular, are suitable candidates for in vitro and in vivo optical imaging applications exploiting the tissue transparency window 700–1000 nm. Moreover, they can be used in sensor chips with integrated optical circuits, where they can exploit the wavelength range 800–900 nm for data transmission trough fiber optic communication.

Our research spans from the study of the optical sensing properties of suitable modified InP colloidal QDs (CQDs) synthesized by wet chemistry methods to a new approach which uses of InP/In0.48Ga0.52P Surface QDs (SQDs) grown by epitaxy on solid substrates.

InP CQs near-infrared (NIR) emission is suitable for in vivo optical imaging of deep tissue in the transmission window 700–1000 nm. Our study is aimed at evaluating the possible use of InP CQDs as O2 sensor both in solution and in solid state for medical application.

Q-dotsInP/In0.48Ga0.52P SQDs are tethered to a semiconductor surface. This represents a major advantage for chem-/bio-sensor and lab-on-chip design, where the integration of CQDs is still challenging. These island-like nanostructures present a fairly large room-temperature NIR emission. The emission intensity increases rapidly and reversibly with methanol vapours. Currently, our goal is to clarify the mechanism of interaction between SQDs and organic molecules.



- R. De Angelis, M. Casalboni, F. De Matteis, F. Hatami, W.T. Masselink, H. Zhang, P. Prosposito
Chemical sensitivity of InP/In0.48Ga0.52P surface quantum dots studied by time-resolved photoluminescence spectroscopy
J. Lumin., 168, 54-58 (2015)

- D. Barettin, M. Auf Der Maur, R. De Angelis, P. Prosposito, M. Casalboni , A. Pecchia
Inter-dot strain field effect on the optoelectronic properties of realistic InP lateral quantum-dot molecules
J. Appl.Phys. 117(9), 094306 (2015)

- D. Barettin, R. De Angelis, P. Prosposito, M. Auf der Maur, M.Casalboni, A. Pecchia,
Model of a realistic InP surface quantum dot extrapolated from atomic force microscopy results
Nanotechnology 25, 195201(1-9), (2014). 

- R. De Angelis, L. D’Amico, M. Casalboni, F. Hatami, W.T. Masselink, P. Proposito,
Photoluminescence sensitivity to methanol vapours of surface InP quantum dot: effect of dot size and coverage
Sensors and Actuators B: Chemical 189, 113-117, (2013).

- R. De Angelis, M. Casalboni, F. Hatami, A. Ugur, W.T. Masselink, P. Prosposito
Vapour sensing properties of InP quantum dot luminescence
Sensors and Actuators B: Chemical, 162, 149–152 (2012).