Direct observation of localized high current densities in GaN films

Local high current densities in areas around dislocations with a screw comp onent might be responsible for the observed high leakage currents in GaN-ba sed electronic devices. Using ballistic electron emission microscopy, threa ding dislocations with a screw component are found to be accompanied by hig h current densities and low effective Schottky barrier heights. The electro nic states responsible for this extremely nonuniform behavior of GaN films are metastable trap states. The experimental results show that acceptor-and donor-like charge traps coexist in the vicinity of dislocations with a scr ew component. (C) 1999 American Institute of Physics. [S0003-6951(99)04616- 1].