Characterization of Semiconductors from Photoconductivity Techniques: Photocarrier Grating Techniques

C. LONGEAUD; J. A. SCHMIDT; J. P. KLEIDER

Photoconductivity and Photoconductive Materials: Fundamentals, Techniques and Applications

John Wiley & Sons Ltd

Lugar: Chichester, West Sussex; Año: 2022; p. 1 - 28

The basic principle of the techniques described in Sections 4.2–4.5 is to illuminate the part of a sample located in the gap between two parallel coplanar electrodes with an interfering light having an adjustable grating spacing. These interferences are obtained by the superimposition of two coherent laser beams polarized in the direction parallel to the electrodes. The angle 𝜃 between the beams fixes the grating spacing Λ. One of these beams has always an intensity much lower, by a factor 10–50, than the other one called the main beam. This main beam sets the steady state of the film, while the other one, which is called the probe beam, induces a small perturbation to this steady state. From the response of the sample to this perturbation, one can extract information on the transport properties of the material, bearing in mind that the experimental conditions to extract this information vary from one experiment to the other. Thus, the parameters deduced from this response may vary from one experiment to the other.