Electrical Characteristics of Ultrathin Atomic Layer Deposited $\hbox{TiO}_{2}$ and $ \hbox{Al}_{2}\hbox{O}_{3}/\hbox{TiO}_{2}$ Stacked Dielectrics on $(\hbox{NH}_{4})_{2}\hbox{S}_{x}$-Treated InP

Amorphous
$\hbox{TiO}_{2}$
film of 5 nm prepared by atomic layer deposition (ALD) on ammonium-sulfide-treated p-type InP shows good interface but slightly higher leakage current mainly from thermionic emission. With a high-bandgap amorphous
$ \hbox{Al}_{2}\hbox{O}_{3}$
of 3 nm prepared also by ALD on
$ \hbox{TiO}_{2}$
, the leakage currents are improved to
$\hbox{3.1} \times \hbox{10}^{-9}$
and
$\hbox{3.3} \times \hbox{10}^{-7}\ \hbox{A/cm}^{2}$
at
$\pm$
2.5 MV/cm. The dielectric constant is about 17.8. The lowest interface state density is around
$ \hbox{6.7} \times \hbox{10}^{11}\ \hbox{cm}^{-2}\hbox{eV}^{-1}$
.