Electron, Optical and Structural Properties of Nanocrystalline Silicon Obtained by Hydrogen Isotope Irradiation of Monocrystals.
Tech Area / Field
- MAT-ELE/Organic and Electronics Materials/Materials
8 Project completed
Senior Project Manager
Mitina L M
Siberian Branch of RAS / Institute of Semiconductor Physics, Russia, Novosibirsk reg., Novosibirsk
- VNIITF, Russia, Chelyabinsk reg., Snezhinsk
- Pacific Northwest National Laboratory, USA, WA, Richland
Project summaryThe purpose of the given Project is to examine the unique material manifesting quantum effects in macroscopic layers. The most attractive feature of such object are connected with its nanocrystalline structure and with the ability to emit the visible light. The material may be obtained by ion beam synthesis in H+, D+ heavy implanted single crystalline or polycrystalline silicon.
Such a synthesis requires the saturation of silicon with high energy H+, D+ ions up to extremely high concentration (about 10E22 cm-3) at various temperature (100-1000 K). That means to reach the doses of the order 10E16-10E18 cm-2 for a reasonable time. VNIITF has necessary sources. A the most acceptable way to reach high doses is to use accelerator included in generator NG-12E and NG-150M.
In ISPH a study of Si-H synthesis was already carried out. Conditions of irradiation producing nanocrystals and arising efficient radiate recombination centers have been found for silan molecules. They need high H+ an D+ implantation dozes (10E17-10E18 cm-2) and elevated temperatures (200-500 °С). On the other hand some preliminary results point to the usefulness of room and more low temperatures. Taking into account the published date and our experience we propose the following solving of the problem:
1. Multi-energy H+and D+ ion implantation, and implantation at different angles of incidence in order tо create homogeneously doped layers.
2. High-doze implantations of 1H and 2H to stimulate the huge nucleation of nanoporos and lanocrystals leading in turn to the high optical yield.
3. Pulse annealing of H+ and D+ ion implanted silicon о facilitate nucleation and to provide for high concentration of low-dimensional nanopores and nanocrystals.
4. Variation of target temperature in order to control the radiation-enhanced crystallization and nucleation and to elucidate the role of silan molecules and siloxens in luminescence.
We anticipate to obtain
1. Optimal parameters for 1H and 2H ion implantation (energy, dose, angle of incidence) to provide the homogeneity throughout the whole silicon layer will be calculated.
2. The dependencies of nanopore and nanocrystal sizes, and of photoluminescence spectra on ion doze (10E16-10E18 cm-2) target temperature and annealing conditions (300-1200 K) and duration (10-3-10 + 5 sec)will be received.
3. The theoretical aspects of the supersaturated solid solution decay of H in Si will be developed.
4. Parameters of zone structure of nanocrystal and interface centres defining the recombination will be determined.
As a result we hope to establish the physical processes governing the synthesis and the decay of the solutions supersaturated with hydrogen isotopes. The structure of nanocrystals emerging in silicon matrix will be defined and the nature of visible photoluminescence will be elucidated. Methods for control of emission spectra and for achievement of high quantum yield will be developed.
Thus the problem of ion-beam synthesis of Si-H compounds by highenergy implantation seems to be very actual and important.
Central Institute of Nuclear Investigations (Rossendorf, Germany) will investigate the photoluminescence spectra of the prepared samples in the green - ultraviolet part of the spectrum, prepare and present reports at the international conferences.