Semiconductor Heterostructures with Quantum Dots
New Technology of Production of High Density And Homogeneity Quantum Dots by Pulsed Laser Deposition Method
Tech Area / Field
- PHY-SSP/Solid State Physics/Physics
3 Approved without Funding
Institute of Radiophysics and Electronics, Armenia, Ashtarak-2
- National Centre for Scientific Research "Demokritos" / Institute of Microelectronics, USA, GA, Athens\nInstitute of Electronic Structure & Laser, Greece, Heraklione\nUniversity of Crete / Department of Chemistry, Greece, Heraklione\nUniversity of Maryland / Department of Materials and Nuclear Engineering, USA, MD, College Park\nUniversity of Virginia / School of Engineering and Applied Science, USA, VA, Charlottesville\nRiso National Laboratory / Department of Optics and Plasma Research, Denmark, Roskilde\nUniversity of Dublin / Trinity College Dublin, Ireland, Dublin\nNational Research Council Canada / Institute for Microstructural Sciences, Canada, ON, Ottawa\nCalifornia State University, Bakersfield, USA, CA, Bakersfield\nGeneral Electric Company / Global Research Center, USA, NY, Niskayuna\nDepartment of the Navy / Naval Research Laboratory, USA, DC, Washington\nUniversity of Alberta / Department of Electrical and Computer Engineering, Canada, AB, Edmonton
Project summaryNew Technology of Production of High Density And Homogeneity Quantum Dots by Pulsed Laser Deposition Method
The development of new technologies to process semiconductor heterostructures with quantum dots (QD), wires and films is at the forefront of Nanotechnology research. The further development of modern opto- and nanoelectronics essentially depends on novel semiconductor processing approaches.
A significant part of the research on developing new nanotechnologies is devoted to technologies of manufacturing heterostructures with QD. The interest in structures with three dimensionally quantized motion, i.e. QD, was originally connected with the problem of creating lasers based on the interband transitions in the bulk semiconductors. Subsequently, the range of applications expanded (e.g. components for computer engineering, solar energy converters, radiation detectors etc.). This is due to the unique optical and the physical properties of heterostructures with QD related to the atom-like energy spectrum of states in QD, which makes their application in opto- and nanoelectronics very promising. Note that practical interest of researchers concentrates on systems with monodispersed QD sizes of about 10 nm and less.
Another rather important property of heterostructures with QD is the surface density of QD, since the response of the system to external action is directly connected with the number of QD, and thus with their density. That is why a problem of new technologies is not simply to obtain ensembles of QD, but also to investigate the possibility to increase the surface density of QD by management of processing parameters, such as deposition rate, substrate temperature, substrate features, etc. Obviously, the solution of this problem demands carrying out complex research on the dependence of QD properties on technologically controllable parameters of their growth already at the nucleation stage.
In this Project it is proposed to investigate the physical foundations and development of new technology of obtaining high density QD by the pulsed laser deposition (PLD) method on materials CdTe-Bi, Si-PbTe, ZnTe- CdTe and multilayered structures on their basis, and also to study their structural, optical and physical properties, with relation to criteria of their usage as active media for generation and detection of electromagnetic radiation and storage devices.
Scope of activity
- Development of physical basis of technology of production by PLD method of quantum dots of high density and uniformity from narrow gap semiconductor Bi* in a matrix of wide gap semiconductor CdTe.
- Development of physical basis of technology of production by PLD method of quantum dots of high density and uniformity from narrow gap semiconductor PbTe in a matrix of wide gap semiconductor Si.
- Development of physical basis of technology of production by PLD method of quantum dots of high density and uniformity from narrow gap semiconductor CdTe in a matrix of wide gap semiconductor ZnTe.
It is important to single out the following features of PLD method that are rather essential from the point of view of practicability of planned researches:
- Stability of deposited layers for one laser pulse;
- Controllability of the energy spectrum of the laser plasma particles;
- High rate of the laser plasma condensate supply on a deposition surface;
- The presence in the forefront of the laser plasma of a significant number of high energy ions and electrons, capable to create additional nucleation centers on the deposition surface
It is proposed that QD-structures will be produced by depositing the narrow band semiconductors in the “island regime”. Also the morphology of island deposition surface of sedimentation will be used as the managing factor promoting the development of high density island, to their ordering. It is proposed that in our researches the deposition surface parameter management will be carried out as follows:
- Creation in advance of the ordered sites for nanocluster nucleation centers by using vicinal substrates;
- Ensuring, due to high speeds of condensate supply, simultaneous creation of high density nucleation islands by formation of significant oversaturation of adatoms;
- Creation of additional nucleation centers due to bombardment of a deposition surface by energetic ions and electrons, contained in laser plasma;
- Ensuring the conditions for occurrence of resonant interaction between atoms (islands) which will promote both the creation of islands and the spatial ordering of QD system as a whole.
- Employing the procedure of instantaneous cessation of island deposition with the subsequent silting by material matching the substrate.
Substrates of relatively big sizes will be used during the production and researches of QD in order to create the combinatorial library of structure and electrical continuity of the deposited films depending on laser pulse intensity and substrate temperature.
During the realization of the Project following aims will be achieved:
1. Development of new technology of production of high density (N≥1012cm-2) QD using PLD method.
Manufacturing of pre-production models of structures
- In−P+CdTe−pCdTe−Bi−pCdTe− …−n CdTe−In
- (In−Sb) −P+Si− pSi−PbTe −pSi−… nSi − (Sb−In)
- (In−Sn) −P+ZnTe−pZnTe−pCdTe−pZnTe−pCdTe …−nCdTe−In
with layers containing QDs from Bi, PbTe, CdTe, correspondingly.
2. Establishment of features of the new nucleation mechanism in a strongly nonequilibrium conditions due to the high rate of instantaneous deposition of high density laser plasma providing a resonant interaction of atoms of a condensate on a substrate.
3. Investigation of the QD production regimes and establishment of the dependence of QD surface density on the substrate temperature and deposition rate.
4. Establishment of the dependence of the surface density of QDs on the temporal regime of stopping and silting processes as one of the major factors of the technological process;
5. Establishment of the deposition regimes ensuring highest possible degree of homogeneity of QD by size and order;
6. Determination of the technological parameters of deposition of Bi QD in CdTe matrix at which the transition of Bi from semi metallic state into semiconductor state is observed.
7. Reduction of the QD deposition temperature to values, excluding matrix-QD interdiffusion.
8. Creation of the database of technological regimes of QD growth, which can be used for automatization of the technological process.
9. Significant expansion of the spectral range of the semiconducting heterostructures (SHS) based on QD from suggested materials.
These results can be used for creation of new element base of computer facilities, lasers, radiation receivers, converters of a solar energy, etc.
Developed SHS with high density QDs will allow to improve considerably the parameters of opto-and nanoelectronic devices.
The realization of the Project will be carried out by 6 Doctors of Phys..Math Sc., 4 Cand. of Phys..Math Sc, 7 physicists and the engineers, having wide experience in the given area, and also the qualified technicians. Most of the participants of the Project during many years were involved in developing new technologies of production of heterostructures by using the PLD method and are participants of ISTC project A-611 ”New Technology Of Preparation Of High Stoichiometric Semiconducting Structures And Solid Solutions By The Method Of Laser Pulse Epitaxy ”. The results of these investigations were published in materials of the international conferences and scientific journals (Proc.MRS 2002, 2003, Measurement science and technology, Inter. Jour. of Infrared and Millimeter Waves, Quantovaya Elektronika (Rus), Journal of Contemporary Physics (Armenian Academy of Sciences), Nanocomposites 2004, etc.).
The proposed Project corresponds to the status of ISTC and is caused by necessity of providing weapons scientists and engineers in the CIS, particularly those who possess knowledge and skills related to weapons of mass destruction, opportunities to redirect their talents to peaceful activities.
* Here the size of the Bi QD is such, that the transition of the Bi from the semimetal state into the semiconductor state has already occurred.
The International Science and Technology Center (ISTC) is an intergovernmental organization connecting scientists from Kazakhstan, Armenia, Tajikistan, Kyrgyzstan, and Georgia with their peers and research organizations in the EU, Japan, Republic of Korea, Norway and the United States.
ISTC facilitates international science projects and assists the global scientific and business community to source and engage with CIS and Georgian institutes that develop or possess an excellence of scientific know-how.