Aluminum and GaN contacts on Si(111) and sapphire

Al and GaN contacts on both Si(111) and sapphire substrates were studied in this letter. After annealing at 450, 520, 600, and 650 degreesC for 35 min under a N-2 flowing ambient, the current-voltage characteristics of Al/GaN contacts on Si(111) substrates were different from those on sapphire ones. The interfacial properties were discussed using the Schottky emission mode l in which the current is proportional to the square of the applied voltage . The metallurgical reactions were analyzed using photoluminescence (PL) sp ectra and x-ray diffraction (XRD). After annealing, blueshifts in the PL sp ectra and new peaks in the XRD data indicated that the wide-band gap interf acial phase AlGaN was formed at the Al/GaN interface. (C) 2000 American Ins titute of Physics. [S0003-6951(00)01746-0].