Effects of annealing conditions on sol-gel dip coated β-Ga2O3 thin films

In this paper, the effects of different annealing conditions on the structural surface morphology and optical properties of the grown beta-Ga2O3 thin films on p-Si (100) substrates via sol-gel dip-coating are reported in detail. The pre-treatment at 500 degrees C after each dipping has led to better adhesion of sol-gel solution on the substrates. XRD measurements confirm the appearance of the crystalline monoclinic phase of beta-Ga2O3. FESEM microscopy and AFM observations show that crack free and densely packed grains morphology of beta-Ga2O3 thin films were formed. FTIR measurements demonstrated that the reflectivity spectra of beta-Ga2O3 thin films are the highest at the annealing temperature of 900 degrees C. EDX spectroscopy revealed an increasing Ga/O ratio with an increasing nitrogen flow rate up to 300 sccm. UV-vis-NIR plots showed that the band gap of beta-Ga2O3 thin films could be tuned when annealed in air and varying N-2 gas flow rate. Finally, all the results revealed that the best annealing conditions for the beta-Ga2O3 thin films are 900 degrees C at 60 min with 300 sccm nitrogen gas flow.