Tailoring
the Interface Quality between HfO<sub>2</sub> and GaAs via <i>in Situ</i> ZnO Passivation Using Atomic
Layer Deposition
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Abstract
We investigated ZnO surface passivation
of a GaAs (100) substrate
using an atomic layer deposition (ALD) process to prepare an ultrathin
ZnO layer prior to ALD–HfO<sub>2</sub> gate dielectric deposition.
Significant suppression of both Ga–O bond formation near the
interface and As segregation at the interface was achieved. In addition,
this method effectively suppressed the trapping of carriers in oxide
defects with energies near the valence band edge of GaAs. According
to electrical analyses of the interface state response on p- and n-type
GaAs substrates, the interface states in the bottom half of the GaAs
band gap were largely removed. However, the interface trap response
in the top half of the band gap increased somewhat for the ZnO-passivated
surface