Photoluminescence and Raman mapping of β-Ga2O3

The semi-insulating single crystal β-Ga2O3 is becoming increasingly useful as a substrate for device fabrication. Fe doping is a method for producing such substrates. Along with Fe dopants, β-Ga2O3:Fe also contains Cr3+. Photoluminescence (PL) emission peaks at 690 nm (1.80 eV) and 696 nm (1.78 eV), as well as a broad feature around 709 nm (1.75 eV), are observed in β-Ga2O3:Fe. PL mapping of the 690 nm emission showed high and low intensity bands due to impurity striations introduced during crystal growth. PL mapping also revealed surface defects showing broad emissions around 983 nm (1.26 eV) and 886 nm (1.40 eV) that were spatially localized, occurring at discrete spots on the sample surface. Raman mapping of an 886 nm emission center revealed peaks at 2878 and 2930 cm−1, consistent with an organometallic or hydrocarbon compound. Raman mapping of the 983 nm center showed a peak at 2892 cm−1. Bright UV emission centers showed Raman peaks at 2910 and 2968 cm−1, which are attributed to Si–CH3 groups that may originate from silica polishing compounds or annealing in a silica ampoule.