The consortium aims to achieve a high quality x-band oscillator through the hybrid integration of a high performance active GaAs HEMT device with that of a high-Q High-Tc superconducting resonator with the entire system functioning at 77K.
Research has been carried out in order to achieve a high quality x-band oscillator through the hybrid integration of a high performance active gallium arsenic high electron mobility transistor (HEMT) device with that of a high-Q high critical temperature superconducting resonator with the entire system functioning at 77K.
The optimum design of a superconducting resonator has been established in the form of a ring coupled to a transmission line. The high performance HEMTs were fabricated using molecular beam epitaxy (MBE) growth techniques and have achieved the required performance levels. There has been success in growing device quality superconductivity films with Laser deposition and direct current (DC) magnetron sputtering. Microwave characterization facilities have been developed for the films and the system. The ability to grow strontium titanate buffers on magnesium oxide using laser deposition has also been developed. The effects of patterning have been analysed using the micro-Raman technique. The Epitaxial lift off (ELO) technique for hybrid integration of the system and a flip chip bonding technique for integration purposes has also been developed.
APPROACH AND METHODS
The consortium intends to fabricate circuits which shall be fully characterised. Through a succession of circuit iterations the optimised component should be reached.
The important aspects of the processing will be addressed by the other members and comprise:
- film growth and patterning (Alcatel Alsthom Recherche)
- buffer layers and passivation (CNR Lamel)
- study of pattern damage (Universidad de Valladolid)
- hybrid integration by epitaxial lift-off (IMEC)
- hybrid integration using a flip-chip technique (LETI).
The experimental determination of the complex conductivity will be decisive to know the behaviour of the high T cuprate oxides.
The development of specific CAD based software will permit a realistic modelling of superconducting planar guided wave structures which is not possible with today's available commercial softwares.
The final demonstrator is particularly relevant for telecommunication systems embarked on board satellites.
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