Thermal Study of Gallium Nitride - Metal Contact

GaN films are prepared by MOCVD method on a sapphiresubstrate. The sample is n-type an semiconductor of 0.5 (mu)m thicknessand carriers concentration 2.2 x 1019cm.3 .Metal contacts are preparedby evaporation of metals on GaN films. I-V characteristics are carriedout under vacuum in the temperature rang from 90 to 300 K. There isa departure from the nonlinear behavior of the current to a linear oneas temperature increases due to the sample series resistance. Thesaturation current is found to be 8.3 x 10.7 A at room temperature;then, it increases with temperature. At room temperature, the barrierheight at zero- bias and the flat band barrier height are calculated atdifferent temperature and they are found to be 0.66 eV and 0.86 eV,respectively. Moreover, the ideality factor has been calculated atdifferent temperature; it, increases with decreasing temperature and itis equal to 1.26 at room temperature. The serial resistant is found to beto 64 Ω at room temperature