Structural and Electrical Properties of EOT HfO₂ (<1 nm) Grown on InAs by Atomic Layer Deposition and Its Thermal Stability

Abstract

We report on changes in the structural, interfacial, and electrical characteristics of sub-1 nm equivalent oxide thickness (EOT) HfO2 grown on InAs by atomic layer deposition. When the HfO2 film was deposited on an InAs substrate at a temperature of 300 °C, the HfO2 was in an amorphous phase with an sharp interface, an EOT of 0.9 nm, and low preexisting interfacial defect states. During post deposition annealing (PDA) at 600 °C, the HfO2 was transformed from an amorphous to a single crystalline orthorhombic phase, which minimizes the interfacial lattice mismatch below 0.8%. Accordingly, the HfO2 dielectric after the PDA had a dielectric constant of ∼24 because of the permittivity of the well-ordered orthorhombic HfO2 structure. Moreover, border traps were reduced by half than the as-grown sample due to a reduction in bulk defects in HfO2 dielectric during the PDA. However, in terms of other electrical properties, the characteristics of the PDA-treated sample were degraded compared to the as-grown sample, with EOT values of 1.0 nm and larger interfacial defect states (Dit) above 1 × 10(14) cm(-2) eV(-1). X-ray photoelectron spectroscopy data indicated that the diffusion of In atoms from the InAs substrate into the HfO2 dielectric during the PDA at 600 °C resulted in the development of substantial midgap states.

Electrical properties and thermal stability in stack structure of HfO2/Al2O3/InSb by atomic layer deposition

“…The difference in oxidation state of diffused In between the two samples can suggest another reaction process for In 2 O 3 related to the reactivity. Comparing the Gibbs free energy of HfO 2 (−1088.2 KJ/mol), Al 2 O 3 (−1582.3 KJ/mol), and In 2 O 3 (−830.7 KJ/mol), we conclude that the reaction of In with Al 2 O 3 or HfO 2 is not possible 6 . Therefore, the oxygen for the formation of In 2 O 3 can be externally supplied from the oxide surface.…”

“…In the case of the InAs substrate, As 2 O 3 and As 2 O 5 states were rarely detected in the as-grown HfO 2 /InAs, whereas elemental As and In 2 O 3 states were clearly measured by the result of interfacial reactions between interdiffused oxygen and the InAs substrate. During the post-deposition annealing process at 600 °C, oxidation states of As 2 O 3 , As 2 O 5 , and In 2 O 3 were generated at the surface region of the HfO 2 6 . In the case of GaSb, the Ga–O and Ga 2 O 3 states were generated on the GaSb surface during the ALD process even at 250 °C 11 .…”

“…These requirements have led to the employment of III–V channel materials and high-κ gate dielectrics 1 . For next-generation large-scale integrations, Hf-based gate (high-κ) dielectrics on III–V compound semiconductors such as InGaAs, GaSb, InP, InAs, and InSb are being seriously considered 2–6 . InSb has the highest bulk mobility (77000 cm 2  V −1 s −1 ) among the III-V materials, so this material is considered to be a particularly attractive III–V compound for high-speed metal-oxide semiconductor field-effect transistors (MOSFETs).…”

Mapping the Coulomb Environment in Interference-Quenched Ballistic Nanowires

“…Reduction of interface state desnity up to a factor of 40 by passivation of InAs surfaces by a HfO 2 overlayer has been reported . However, we cannot rule out an alternate explanation based on compensating acceptor states introduced by HfO 2 . ,, …”

Indium Diffusion Behavior and Application in HfO2‐Based Conductive Bridge Random Access Memory

“…Past research has shown that indium (In) can inject into HfO 2 due to high temperature or an electric field . In this article, based on this result, In is used as the top electrode, and the electric field is used to drive In into the switching layer.…”