In Situ SiO₂ Passivation of Epitaxial (100) and (110)InGaAs by Exploiting TaSiO Atomic Layer Deposition Process

Area of Science:

• Materials Science
• Semiconductor Physics
• Nanotechnology

Background:

• Indium Gallium Arsenide (InGaAs) is a crucial material for advanced electronic devices.
• Developing stable high-κ gate dielectrics on InGaAs is challenging due to interface issues.
• In situ passivation techniques are needed to improve the reliability of InGaAs-based devices.

Purpose of the Study:

• To report an in situ silicon dioxide (SiO2) passivation technique during atomic layer deposition (ALD) of tantalum silicon oxynitride (TaSiO2) gate dielectrics.
• To investigate the epitaxy and interface properties of InGaAs on InP substrates with ALD-grown TaSiO2.
• To determine the band offsets and assess the potential for reduced gate leakage in InGaAs devices.

Main Methods:

• Solid-source molecular beam epitaxy (MBE) for InGaAs growth on InP substrates.
• In situ ALD of TaSiO2 with an intentionally formed SiO2 interfacial passivating layer (IPL).
• X-ray reciprocal space mapping (RSM) for epitaxy analysis.
• Cross-sectional transmission electron microscopy (TEM) for interface characterization.
• X-ray photoelectron spectroscopy (XPS) for chemical composition and band offset determination.

Main Results:

• Quasi-lattice matched InGaAs epitaxy was achieved on InP substrates.
• Sharp heterointerfaces were observed between ALD TaSiO2 and InGaAs epilayers.
• An approximately 0.8 nm SiO2 IPL was consistently formed during TaSiO2 deposition.
• Significant valence band offsets (ΔEV) of 2.52 ± 0.05 eV (100) and 2.65 ± 0.05 eV (110) were measured.
• Conduction band offsets (ΔEC) were calculated to be 1.3 ± 0.1 eV (100) and 1.43 ± 0.1 eV (110).

Conclusions:

• The in situ SiO2 passivation during ALD of TaSiO2 effectively creates stable interfaces on InGaAs.
• The large valence and conduction band offsets indicate potential for improved gate dielectric performance.
• This technique is promising for developing thermodynamically stable high-κ dielectrics on InGaAs for low-power electronic applications.