Optical and Electrical Properties of Tin Oxide Films

Abstract

The electrical and optical properties of the transparent conducting tin oxide films were studied experimentally. The observed Hall effect and Seebeck effect show that the present specimens are n -type conductor whose carrier density is 10 19 ∼10 20 cm -3 . The optical measurements made it clear that the fundamental energy gap was about 4 ev and the plasma frequency of the conducting carriers lied in the near infrared region. By comparing the observed optical transmission and reflection with the theoretical values which can be calculated with the electrically measured constants, the effective mass of the carriers was determined to be about 1/5 of the free electron mass. It will be discussed in conclusion that, to satisfy the thermoelectric power relation with this small effective mass, we must assume that the Coulomb scattering of impurity ions is the predominant scattering mechanism in the transparent conducting tin oxide films.