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| AFM image of quantum dots |
Low dimensional structures have recently attracted much attention and opened new avenues in physics research. Three-dimensional quantum confinement of electron and holes in quantum dots is indeed expected to enable novel physical phenomena, and to significantly enhance the performance of various optoelectronic components. Acreo has recently developed growth techniques to fabricate InAs/InGaAs/GaAs quantum dots optimised for applications ranging from night vision to low-cost telecom devices. First prototype devices have been successfully evaluated in our labs and show large promises for future optoelectronic components.
Self-organisation
InAs/InGaAs/GaAs quantum dots are grown at Acreo by MOVPE. Quantum dots are self-assembled using the Stranski-Krastanov growth mode, and their density and uniformity can be repeatedly and accurately tuned by controlling specific growth parameters.
Modelling and characterisation
In collaboration with university partners at KTH, Linköping and Lund, Acreo has developed advanced modelling and characterisation tools (microscopy- and spectroscopy-based) for the design and evaluation of quantum dot materials.
Quantum dot infrared photodetectors (QDIP)
First prototypes have been fabricated and tested. The main advantages of quantum dots are:
- Lower dark current due to the 3D-confinement of carriers
- Possibilities for higher operating temperature, which consequently will lead to a cheaper camera system.
- Absorption of radiation at all angles of incidence, since the electrons are confined in all directions, which will lead to simpler fabrication process.
- Longer lifetime of excited carriers than in quantum wells, which will increase the probability for an excited electron to contribute to the photocurrent and will therefore increase responsivity.
Quantum dot lasers and amplifiers
First prototypes have been fabricated and tested. The main advantages of quantum dots are:
- Lower power consumption
- Higher temperature stability
- Amplifiers: Decrease of gain recovery time, and broadband gain (300nm) due to inhomogeneous broadening
Novel devices
Unique features of quantum dots may lead to the development of novel devices that could not be fabricated with conventional materials. A particular example is the use of the long coherence time property of quantum dots to develop compact and low-cost tunable optical buffer memories by electromagnetically induced transparency.
Contact us to discuss performance and applications of quantum dot materials and devices.
Recent publications
- L. Höglund, E. Petrini, C. Asplund, H. Malm, J. Y. Andersson, ” Optimising uniformity of InAs/(InGaAs)/GaAs quantum dots grown by metal organic vapor phase epitaxy”, 8th International Conference on Atomically Controlled Surfaces, Interfaces and Nanostructures, June 2005