Fe³⁺ and Cr³⁺ Photoluminescence of Fe doped β-Ga₂O₃

Semi-insulating single crystalline β-Ga₂O₃ is becoming increasingly useful as a substrate for device fabrication. Fe doping single crystalline β-Ga₂O₃ is a method for producing such substrates. Cr³⁺ Photoluminescence (PL) emission peaks at 690 nm (1.80 eV) 696 nm (1.78 eV), as well as a broad feature around 715 nm (1.74 eV), are observed in Fe-doped β-Ga₂O₃. PL mapping showed signatures of Cr³⁺ and Fe³⁺ defects. Intriguingly, Fe³⁺ defects showed a broad 950nm (1.3 eV) peak that was highly localized, occurring at discrete spots on the sample surface. This suggests either that there is not a homogenous distribution of Fe in the sample, or that the Fe³⁺ emissions observed are specific to localized regions of Fe³⁺ in α-Ga₂O₃. PL mapping also revealed bands of high and low intensity that could be due to Cr³⁺ impurity striations introduced during crystal growth.