Doping induced surface chemistry dictating the characteristics of Schottky contacts to III-V nitride semiconductors

While lightly doped semiconductors are preferred for Schottky contacts, heavily doped semiconductors are preferred for Ohmic contacts. The upper limit of doping for Schottky contacts and the lower limit of doping for Ohmic contacts have not, however, been quantified. To address this problem, the influence of doping induced surface chemistry on the electrical characteristics of Schottky diodes has been studied. Hall measurement, current-voltage measurements, and transmission electron microscopy have been performed. The most remarkable observation of the study is a relationship between the surface dislocation density and the ideality factor of the Schottky diodes. The observation leads to a conclusion that the upper limit of the semiconductor doping for Schottky diodes should be such that it leads to negligible barrier height reduction without the creation of excessive surface dislocation density. (c) 2006 American Institute of Physics.