Low-Temperature As-Grown Crystalline β-Ga2O3 Films via Plasma-Enhanced Atomic Layer Deposition
Saidjafarzoda Ilhom1, Adnan Mohammad1, Deepa Shukla1,2
1Department of Electrical & Computer Engineering, University of Connecticut, 371 Fairfield Way, Storrs, Connecticut 06269, United States.
ACS Applied Materials & Interfaces
|February 10, 2021
Summary
This study demonstrates low-temperature crystalline gallium oxide (Ga2O3) film growth using plasma-enhanced atomic layer deposition (PEALD) with in situ plasma annealing. This method successfully converts amorphous films into crystalline beta-Ga2O3 without high-temperature treatments.
Area of Science:
- Materials Science
- Thin Film Deposition
- Semiconductor Processing
Background:
- Gallium oxide (Ga2O3) is a promising wide bandgap semiconductor.
- Low-temperature deposition methods are crucial for cost-effective semiconductor manufacturing.
- Achieving crystalline Ga2O3 at low temperatures typically requires high-temperature post-annealing.
Purpose of the Study:
- To develop a low-temperature plasma-enhanced atomic layer deposition (PEALD) process for crystalline Ga2O3 films.
- To investigate the effect of in situ Ar plasma annealing on film properties.
- To enable crystalline Ga2O3 growth without high-temperature post-deposition annealing.
Main Methods:
- Plasma-enhanced atomic layer deposition (PEALD) using triethylgallium (TEG) and Ar/O2 plasma.
- Substrate temperatures ranging from 150-240 °C.
- In situ Ar plasma annealing integrated into the PEALD cycle, with varying radio-frequency (rf) power (50-300 W).
Main Results:
- PEALD without annealing produced amorphous Ga2O3 films.
- In situ Ar plasma annealing enabled the growth of monoclinic β-Ga2O3.
- Optimized annealing (250 W) resulted in enhanced crystallinity, density (5.60 g/cm³), near-ideal stoichiometry (O/Ga ~1.44), and low carbon content (~5 at. %).
Conclusions:
- In situ Ar plasma annealing is an effective method for low-temperature synthesis of crystalline β-Ga2O3 films.
- This PEALD approach bypasses the need for high-temperature post-deposition annealing.
- The developed method offers a pathway for cost-efficient fabrication of Ga2O3-based electronic devices.
