Keywords: semiconductors, heterostructures, 2D electron gas
Start Date: 1 January 1994 / Status: finished / Duration: 36 months
[ participants / contact]
The effect of dislocations and other extended defects on the electrical and optical properties of semiconductors has been widely studied in bulk semiconductors, but very limited work has been published about how they affect transport and optical properties in 2D and other low dimensional heterostructures. This point is worth studying, because i.e. misfit dislocations are likely to occur in strained heterostructures. So, the project involves an investigation of how the basic transport phenomena (magnetotransport, Shubnikov-de Haas and quantum Hall effects) are affected by dislocations and other extended defects.
The experimental part of the project involves the lattice matched GaAlAs/GaAs in InGaAs/InP systems and strained InGaAs/GaAs heterostructures. Growth and characterisation of the corresponding materials have been performed noticeably by photoluminescence, Raman and X-rays diffraction. Selective introduction of dislocations has been achieved by bending or during growth and observed by transmission electron microscopy, X-rays diffraction and cathodoluminiscence techniques. The main experimental method has been the study of the magnetotransport on the above structures containing 2D electron gas. A comparison of different approaches has been performed. The effect of different scattering mechanisms induced by dislocations has also been calculated.
For a quantitative approach of the role and properties that extended defects may have on the properties of 2D electron gas, three directions have been followed: a characterisation of heterostructures that are free of extended defects; the development of methods for controlling the introduction of dislocations and the measurement of their effects on the quantum transport properties of 2D electron gas as well as on the minority carrier recombination properties; and the development or improvement of theoretical approaches needed for the interpretation of the experimental results.
Results achieved so far have been presented at international conferences and published in theoretical and technical journals. A list of over ten publications can be requested from the coordinator.
Université des Sciences et Technologies de Lille
URA 234 CNRS
F-59655 Villeneuve d'Ascq Cedex, F
Université des Sciences et Technologies de Lille, F
Research Institute for Technical Physics, HU
Prof. Jean-Louis Farvacque
Tel: +33 20 434 867
Tel secr: +33 20 434 967
Fax: +33 20 436 591
GASTOR - CP93-8252, May 1997
please address enquiries to the ESPRIT Information Desk
html version of synopsis by Nick Cook