1：Experimental Design and Method Selection:

Ga2O3 films were deposited on c-sapphire substrates at 250°C by PEALD using trimethylgallium (TMGa) as the Ga precursor and O2 plasma as the oxidant. The plasma was generated to activate oxygen gas during the O2 gas pulse, and the RF plasma power was 2000 W.

2：Sample Selection and Data Sources:

The as-deposited Ga2O3 films were annealed at 1000°C in oxygen atmosphere for 30 min, 1 h, and 2 h.

3：List of Experimental Equipment and Materials:

XPS for chemical compositions and bonding states, XRD for crystal structure, AFM for surface morphologies, and UV–vis–NIR spectrophotometer for optical transmittance measurements.

4：Experimental Procedures and Operational Workflow:

The deposition cycle consisted of four pulses in sequence: TMGa vapor pulse with 60 sccm N2 carrier gas for

5：1 s, an N2 purge gas pulse for 5 s, an O2 plasma gas pulse for 20 s, and an N2 purge gas pulse for 5 s. This cycle was repeated for 400 times. Data Analysis Methods:

The optical band gap was obtained by extrapolating the straight-line portion of the plot of (ahv)^2 as a function of photon energy hv.