1：Experimental Design and Method Selection:

The study used electron-beam evaporation for depositing ZnO, MgZnO, and CdZnO thin films on Si/SiO2 substrates with chromium interdigitated electrodes. Characterization included XRD, AFM, FESEM, PL, UV, and Raman spectroscopy to analyze properties. Gas sensing was performed in a controlled chamber with an IV source meter, testing resistance changes with CO gas concentration and temperature.

2：Sample Selection and Data Sources:

Si wafers were cleaned using RCA-1 and RCA-2 processes. Target materials (99.99% purity) were purchased from Taewon Scientific Co. Ltd, and chemicals from Merck, India. Sensing layers and electrodes were deposited with specific rates and pressures.

3：99% purity) were purchased from Taewon Scientific Co. Ltd, and chemicals from Merck, India. Sensing layers and electrodes were deposited with specific rates and pressures. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: E-beam evaporation system (deposition rate 0-10 ?/sec, pressure ~4×10^-6 mbar), Rigaku TTRAX III X-ray Diffractometer, Agilent 5500 AFM, Zeiss GeminiSEM 500 FESEM, Perkin Elmer LS 55 fluorescence spectrometer, Shimadzu UV-2600 spectrophotometer, AIRIX Corp. STR-750 Raman spectrometer, Keithley 2450 IV source meter, Mass Flow Controllers (10 SCCM and 1000 SCCM).

4：Experimental Procedures and Operational Workflow:

Substrates were cleaned, thin films deposited via e-beam evaporation, electrodes patterned. Characterization techniques applied to assess structural, morphological, optical properties. Gas sensing tests conducted at various temperatures and CO concentrations, measuring resistance changes.

5：Data Analysis Methods:

Sensor response calculated as R0/R. Structural parameters from XRD, surface roughness from AFM, band gap from Tauc plot, gas response analyzed with respect to temperature and concentration.