Sputter-deposited W-based contacts on p-GaN (NA-1018 cm"3) display non-ohmic behavior independent of annealing temperature when measured at 25 °C. The transition to ohmic behavior occurs above ~250 °C as more of the acceptors become ionized. The optimum annealing temperature is ~700 °C under these conditions. These contacts are much more thermally stable than the conventional Ni/Au metallization, which shows a severely degraded morphology even at 700 CC. W-based contacts may be ohmic as-deposited on very heavily doped n-GaN, and the specific contact resistance improves with annealing up to -900 °C.
|Journal||Materials Research Society Symposium Proceedings|
|State||Published - 1999|