Light Emitting Structures for Optoelectronics
Light Emitting Rare Earth Doped Si-based Structures for Optoelectronics
Tech Area / Field
- PHY-SSP/Solid State Physics/Physics
- INF-ELE/Microelectronics and Optoelectronics/Information and Communications
- MAT-ELE/Organic and Electronics Materials/Materials
- PHY-OPL/Optics and Lasers/Physics
3 Approved without Funding
Russian Academy of Sciences / Physical Technical Institute, Russia, St Petersburg
- Institute of Physics of Microstructures, Russia, N. Novgorod reg., N. Novgorod\nNPO Orion, Russia, Moscow
- Universiteit Amsterdam / Van der Waals-Zeeman Instituut, The Netherlands, Amsterdam\nJohannes Kepler Universitat Linz / Institut fuer Halbleiter- und Festkoerperphysik, Austria, Linz\nKing's College London, UK, London
Project summaryDevelopment of effective light-emitting Si-based structures is a key problem of silicon optoelectronics. An intensive interband radiative recombination is impossible here because silicon is not a direct-band material. One way of solving the problem is to incorporate rare-earth elements into silicon and excite intra-atomic radiative transitions. Since the mid-90s a number of leading research centres in the USA, Italy, the Netherlands, Austria, Russia, Germany and Japan and have been involved in intensive research to produce light-emitting Er-doped Si structures. Such structures emit at an 1.54 mm wavelength corresponding to the minimum losses and dispersion in fiber optical communication lines. However, for all the impressive results obtained heretofore, the intensity of Er ion electroluminescence has to be about two orders of magnitude higher to comply with practical applications. At the same time, given current understanding of the Si:Er material properties and the mechanisms behind the Er ions luminescence it can be predicted that development of a semiconductor laser on the Si:Er system basis is a matter of immediate future. To solve these two problems will take both searching for new ways of suppressing nonradiative recombination channels in fabrication of light-emitting structures, and a thorough investigation of new optically active centres, mechanisms of their excitation and deexcitation, along with the processes of formation and transformation of defects in silicon with a high content of rare-earth elements and co-dopants.
The authors of the Project – scientists at the Ioffe Physical-Technical Institute, State Unitary Enterprise "RD&P Centre "Orion" and the Institute for Physics of Microstructure – have obtained a number of novel results including identification of optically and electrically active centres containing rare-earth impurities, observation of temperature-induced enhancement of the Er ion electroluminescence intensity, development of models for excitation of rare-earth ions through the energy transfer from charge carriers to rare earth ions, first observation of Ho ion luminescence in semiconductors. The experience and facilities available with the Russian team provide a solid basis for launching a new ISTC project aimed at conducting a fundamental research.
The objective of the project is the development of a scientific and technological basis for the fabrication of light-emitting rare earth (RE) doped Si-based structures for optoelectronics. To achieve the objective, three main problems are planned to solve:
1. Development of technology of high-efficiency light-emitting Si-based structures doped with rare earth impurities (Er, Ho, Tm, Yb),. including structures with a specified type of emitting centres, high concentration of such centres, and with an optimal excitation transfer to the internal shell of a rare-earth ion;
2. Thorough investigation into the origin of optically and electronically active centres containing rare-earth elements, the mechanisms of their excitation and deexcitation in the monocrystalline silicon matrix with a view to providing maximum possible quantum efficiency and intensity of photo- and electroluminescence in Si:RE structures;
3. Searching for ways to achieve stimulated light emission in structures based on Si and Si-Ge doped with rare-earth impurities (REI).
In investigations main attention will be given to the Er impurity emitting at the 1.54 mm wavelength which is most widely used in optical fiber communication systems.
To solve the problems, the following technical approaches will be used:
– Development of a technology of high-efficiency light-emitting structures on the basis of RE doped silicon with a preset composition of radiating and electrically active centres (problem 1) will involve development of the methods of high temperature ion implantation, solid-phase /molecular-beam/ sublimation molecular-beam epitaxy. Main attention will be given to investigation of mechanisms underlying optical activation of rare earth impurities in growing layers and to studies of background impurity effects on the layers properties.
– To establish the mechanisms of excitation transfer from the electron subsystem of a crystal to RE ions and identify the optimum radiating centre with a view to increasing the photo- and electroluminescence intensity of RE ions (problem 2), a study will be conducted on the interaction between luminescence-activating impurities (O, C, N, F, S) and rare earth ions in structures prepared in different technologies, and on the sensitization effect arising by Yb doping of Si:Er structures. Strong efforts will be given to determine the role of heteroboundaries and quantum-size effects in increasing luminescence efficiency of RE ions, to be followed by development of various quantum-size structures on the basis of RE doped Si and SiGe. The milestones to be achieved for the maximum electroluminescence intensity are as follows: investigations of the energy spectra and microstructure of optically and electrically active RE-related centres induced by the techniques used; determination of special features and regularities of the electrical and optical properties of Si-based structures doped with different REI; search of the optimal conditions of the doping with RE ions to create the effective light-emitting centres; optimization of the concentration profiles of RE ions and other dopants.
– Structures based on Si:Er, Si:Ho, Si/SiGe:Ho and Si/SiGe:Er with various contents of Ge and REI will be developed to achieve stimulated light emission (problem 3). Theoretical and experimental investigations of the excitation and deexcitation mechanisms of RE ions and of the realization of three-level excitation scheme for an inverse population in Er3+ and Ho3+ ions will be done as well as the construction and technology tailoring of laser structures will be elaborated.
Work within the Project will involve an extensive range of methods for study of structural, electrical and optical properties of light-emitting layers. Considerable importance will be attached to the development of models for description of defect formation processes, energy transfer between free charge carriers and rare earth ions, excitation and deexcitation of luminescence.
The main anticipated result is the development of a scientific and technological basis for the fabrication of high-efficiency light-emitting Si-based structures doped with different REI. It allows one to estimate prospects of the use of REI-doped Si-based light-emitting structures for optoelectronics and determine conditions for stimulated light emission in the structures.
The Collaborators: Prof. C.A.J.Ammerlaan, Head of Semiconductor Physics Research Department at Van der Waals-Zeeman Institute of Amsterdam University (The Netherlands), and Prof. W.Jantsch, Head of Subpision of Solid State Spectroscopy at the Institute for Semiconductor and Solid State Physics of Linz University (Austria) will participate in planning the work, conducting joint research, discussion of results and preparation of joint publications.
The proposed Project objectives comply with the ISTC goals which are to grant the NIS scientists formerly involved in the development and production of weapons an opportunity for contributing their potential to solving of the R&D problems of international significance. Support of the Project will promote integration of the participating scientists into the worldwide scientific community and will open long-term prospects for them in their professional field.
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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.