Electronic Diffusivity Measurement in Silicon by Photothermal Microscopy

Benoît C. Forget, Isabelle Barbereau, Danièle Fournier
Laboratoire d'Instrumentation, Université Pierre & Marie Curie
ESPCI, 10 rue Vauquelin, 75231 Paris cedex 05, FRANCE

Suneet Tuli and Amalendu B. Battacharyya
C.A.R.E., Indian Institue of Technology, Hauz Khas, New Delhi 110016, INDIA

abstract
In this paper we demonstrate that a photothermal microscopy experiment can be used to determine the electronic diffusivity (or carrier mobility) in the same way it is now widely used to measure locally thermal diffusivity of various non semiconductor materials. The main difficulty lies in the fact that in order to separate thermal and carrier diffusion, the experiment must be performed for a relatively large distance between the pump and probe beams. Photothermal signals are therefore rather weak and great experimental care must be taken. We present and discuss experimental results on Si.