Atomic-Level Sn Doping Effect in Ga₂O₃ Films Using Plasma-Enhanced Atomic Layer Deposition

Area of Science:

• Materials Science
• Semiconductor Physics
• Thin Film Technology

Background:

• Gallium Oxide (Ga2O3) is a promising wide-bandgap semiconductor for power electronics and transparent devices.
• Controlling doping in Ga2O3 is crucial for tailoring its optoelectronic properties.
• Atomic layer deposition (ALD) offers precise control over thin film composition and structure.

Purpose of the Study:

• To investigate the effects of tin (Sn) doping on the properties of Ga2O3 films.
• To systematically analyze changes in chemical state, microstructure, optical, and electrical characteristics.
• To provide a foundation for designing Sn-doped Ga2O3 transparent devices.

Main Methods:

• Plasma-enhanced atomic layer deposition (PEALD) for Sn-doped Ga2O3 film deposition.
• X-ray reflectivity (XRR) and spectroscopic ellipsometry for structural and optical analysis.
• Analysis of chemical states, band alignment, and electrical properties (including C-V characteristics).

Main Results:

• All Sn-doped Ga2O3 films exhibited high transparency (>90%) in the UV-visible range.
• Sn doping influenced film density, refractive index, and extinction coefficient.
• Increased Sn content led to higher Sn-O bonding, reduced oxygen vacancies, and a decreased bandgap (4.73 to 4.31 eV).
• Breakdown mode shifted from hard to soft breakdown with increasing Sn content.
• Sn-doped Ga2O3 films demonstrated large permittivity.

Conclusions:

• Sn doping is an effective method to tune the properties of Ga2O3 films.
• The observed changes in band structure and electrical properties are linked to reduced oxygen vacancies.
• These findings support the use of Sn-doped Ga2O3 in transparent electronic devices.