Optical properties of semiconductors, dielectrics and metals play a key role in the
development of thin film solar cells. While these devices belong to photon photodetectors both the
photon and wave nature of light affects their performance. Some of these problems are discussed in
this chapter. The efficiency of photogeneration of free carriers by light as well as its spatial
distribution is taken into consideration. This distribution is strongly affected by light interfering in a
structure of many thin films. The possible geometrical and optical inhomogeneities of the solar cell
structure are discussed. A few methods of determining surface and averaged overall film thickness
refractive indices of semiconductor materials are presented. Techniques for determining different
components of absorption of light in semiconductors are also reported. Examples of optical methods
useful for determining essential parameters of semiconductors (e.g., optical energy gap, carrier
diffusion length, and parameters of electron states) are presented as well.
Keywords: Semiconductors, transmittance, reflectance, quantum efficiency of photogeneration,
linear distribution of intensity of reflected and transmitted radiation, graded energy gap
semiconductor, optical properties of multilayer structure, amorphous silicon, refractive index,
absorption coefficient, spatial distribution of radiation intensity, photogeneration of free carriers,
recombination, electronic states parameters, steady state photocarrier grating, photoconductivity,
photoelectromagnetic effect, optical inhomogeneity.
