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In this study, several measurement techniques
were used to analyze the electric characteristics and traps
in unintentionally doped n-type GaN grown by metal organic
chemical vapor deposition.I-V measurements on Schottky diodes
indicates the forward current appears due to thermionic field
emission of electrons through the Schottky barrier, because
there are high trap concentrations near the surface region. On
the other hand, the electrons tunnel through the Schottky
barrier at large reverse voltage, and through a smaller barrier
by the assistance of a trap E2 at small reverse voltage. C-V
measurements indicate the smaller V/III ratios, the larger
carrier concentrations because of the increase of nitrogen
vacancies. Therefore,the series resistance becomes smaller and
capacitance larger. Schottky barrier height is much larger than
the theoretical value of 0.84eV at low temperature, and is
smaller at high temperature. Studies by transient capacitance
measurements revealed the presence of a new majority-carrier
trap with the activation energy of 1.34eV.
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