Possibilities of single production of the scalar leptoquark and also of its supersymmetric partner in polarized-gamma-e beams are studied in E6 superstring theories. Expressions for the differential and total cross sections are obtained and analyzed. It is shown that the scalar leptoquark of mass 300 GeV can be detected even for a very small interaction constant lambda-2/4-pi almost-equal-to 10(-3)alpha, and its supersymmetric partner can be detected for lambda-2/4-pi almost-equal-to 10(-2)alpha. The spin asymmetry due to the photon-beam polarization and the effect of this polarization on both the differential and the total cross sections are studied in detail. It is shown that study of the spin asymmetry and the effect of the photon-beam polarization can be used to extract information about the leptoquark masses.