S. Belkouch et al., GAAS SURFACE CHEMICAL PASSIVATION BY (NH4)(2)S+SE AND THE EFFECT OF ANNEALING TREATMENTS, Solid-state electronics, 39(4), 1996, pp. 507-510
We report on a new Se chemical passivation [(NH4)(2)S+Se] for GaAs sur
faces. We compare our Se passivated surfaces with (NH4)(2)S+S [(NH4)(2
)S-x] passivated surfaces by preparing Al-nGaAs Schottky diodes and su
bmitting them to cumulative annealing treatments. We find that with or
without an annealing treatment the Schottky barriers are consistently
closer to the ideal value (0.2 eV) when the GaAs surfaces are treated
with the (NH4)(2)S+Se rather than the (NH4)(2)S-x chemical solution.
This indicates that (NH4)(2)S+Se surface passivation is more effective
in reducing the surface state density and in unpinning the Fermi leve
l than the (NH4)(2)S-x passivation treatment. These results are attrib
uted to the complementary passivation role of the S and the Se on the
GaAs surface. Also, the annealing treatment plays an important role in
the control of the barrier height in both kinds of passivation.