Speaker
Prof.
Anthony Peaker
(Photon Science Institute, University of Ma)
Description
A comprehensive understanding of impurities and lattice defects has been central to the development of semiconductor devices. The electronic properties of these impurities depend on the chemical species, the site of the impurity in the lattice and its possible complexing with other impurities and lattice defects such as vacancies. A very important tool in the study of defects and impurities is Deep Level Transient Spectroscopy (DLTS). This has been used since 1990 at ISOLDE in a number of innovative experiments where species have been implanted which undergo nuclear transmutations.
Unfortunately conventional DLTS provides a spectrum of the carrier emission from the defect with rather low resolution. The end result is that very little physical information can be derived from DLTS and this has proved to be a major problem in many applications and has limited the scope of its use at ISOLDE. However over the last decade a major advance in DLTS has been achieved which removes all the instrumental broadening from the measurement resulting in an order of magnitude improvement in energy resolution. This is generally referred to as Laplace DLTS or LDLTS (see www.laplacedlts.eu). The new technique moves DLTS from being a fingerprinting tool to the realm of an important probe of defect physics. During the summer of 2010 a LDLTS system was commissioned at ISOLDE and has been tested with an implant of 195Hg > 195Au > 195Pt. After annealing and diffusion this implant gave a volume concentration of ~10^12 cm-3 which is very typical of the levels of interest in semiconductor devices.
In the talk LDLTS spectra taken at ISOLDE will be presented and examples shown of how the technique can be used to probe the electronic properties of defects and their local environment in the lattice. Finally some problems will be outlined to which the installation could be applied.
Summary
An outline of the capabilities of a new installation at ISOLDE of high resolution deep level transient spectroscopy for semiconductor research will be given in this presentation.
Author
Prof.
Anthony Peaker
(Photon Science Institute, University of Ma)
Co-authors
Dr
Karl Johnston
(ISOLDE, CERN)
Dr
Vladimir Markevich
(Electrical Engineering and Electronics, University of Manchester)
