1：Experimental Design and Method Selection:

The study uses remote plasma-enhanced atomic layer deposition (RPEALD) to deposit Ga2O3 thin films, with in-situ NH3 plasma pretreatment to modify substrate surfaces. The rationale is to enhance deposition rates and improve interface quality for semiconductor applications.

2：Sample Selection and Data Sources:

Substrates include 2-inch n-Si (100) wafers and GaN epi wafers (~1 × ~1 cm2). They are cleaned ex-situ using acetone, isopropyl alcohol, de-ionized water, and specific solutions (HF for Si, NH4OH for GaN) to remove native oxides.

3：List of Experimental Equipment and Materials:

Equipment includes RPEALD system (PICOSUN R-200 Advanced), ellipsometry (M2000DI, J.A. Woollam), HR-TEM (Tecnai G2 F20 S-Twin, FEI), AFM (Dimension ICON, Burker), XPS (PHI 5000 Versa Probe II, ULVAC-PHI), and TOF-SIMS (IONTOF). Materials include TMG (5N purity), ultra-pure O2 (6N), N2 (5N), NH3, and substrates (Si and GaN).

4：Experimental Procedures and Operational Workflow:

Substrates are cleaned and placed in the RPEALD chamber. In-situ NH3 plasma pretreatment is conducted at room temperature (RF power 2000 W, 13 s NH3 plasma, 6 s N2 purge, 10-70 cycles). Ga2O3 deposition follows with cycles of TMG pulse (0.1 s), N2 purge (6 s), O2 plasma (13-20 s, RF power 2800 W), and N2 purge (6 s) at temperatures from 100 to 400 °C. Thickness, morphology, and composition are characterized using ellipsometry, AFM, XPS, TOF-SIMS, and HR-TEM.

5：1 s), N2 purge (6 s), O2 plasma (13-20 s, RF power 2800 W), and N2 purge (6 s) at temperatures from 100 to 400 °C. Thickness, morphology, and composition are characterized using ellipsometry, AFM, XPS, TOF-SIMS, and HR-TEM. Data Analysis Methods:

5. Data Analysis Methods: Data analysis includes fitting XPS spectra with CasaXPS software, calculating film thickness from ellipsometry and XPS angle-resolved measurements, and using SIMS for depth profiling. Statistical methods are not explicitly detailed, but linear fitting is used for thickness estimation.