In this paper, we study the Debye screening length (DSL) in ultrathin films of optoelectronic materials in the presence of light waves. The solution of the Boltzmann transport equation on the basis of the newly formulated electron dispersion laws will introduce new physical ideas and experimental findings under different external conditions. It has been found, taking ultrathin films of n-Hg1-x,CdxTe, as an example, that the respective two-dimensional (2D) DSL in the aforementioned materials exhibits decreasing quantum step dependence with the increasing film thickness, surface electron concentration, light intensity and wavelength, respectively, with different numerical values. The nature of the variations is totally band structure dependent which is influenced by the presence of the different energy band constants. The strong dependence of the 2D DSL on both the light intensity and the wavelength reflects the direct signature of the light waves. The well-known result for the 2D DSL for nondegenerate wide gap materials in the absence of any field has been obtained as a special case of the present analysis under certain limiting conditions and this compatibility is the indirect test of our generalized formalism. Besides, we have suggested an experimental method of determining the 2D DSL in ultrathin materials in the presence of light waves having arbitrary dispersion laws
