PLASMA-ENHANCED EVAPORATION OF SIO2-FILMS FOR MBE-GROWN MOS DEVICES

A low-energy oxygen plasma was generated by a UHV-compatible plasma so urce. Throughout the plasma, silicon was evaporated and thin SiO2 film s were deposited at room temperature. These films were characterized w ith respect to their stoichiometric and optical properties by Auger el ectron spectroscopy (AES), Rutherford backscattering spectrometry (RBS ) and ellipsometry. The SiO2 layers show a thickness between 25 and 60 nm. The measured refractive indices confirm the stoichiometry of the films ast proved with AES and RES. AES depth profiles also show that t he SiO2 layers are homogeneous. For electrical characterization, MOS d iodes were fabricated. From capacitance-voltage and conductance-voltag e measurements an oxide charge density of Q(ox) approximate to 10(-8) C/cm(2) and an interface trap density of D-it approximate to 1 x 10(11 ) eV(-1) cm(-2) was deduced for [111] substrates without any annealing .