Optical and Electronic Energy Band Properties of Nb-Doped β-Ga2O3 Crystals

Systemic investigations are performed to comprehend the structural, optical, and electrical characteristics of four niobium (Nb) doped beta-Ga2O3 crystals (beta-Ga2O3:Nb) grown by the optical floating zone (OFZ) method. All of the beta-Ga2O3:Nb crystals revealed monoclinic phases and good crystalline qualities. While the different Nb doped (i.e., 0.0001 mol%, 0.01 mol%, 0.1 mol% and 0.5 mol%) samples exhibited slightly changed bandgap energies E-g (equivalent to 4.72 eV, 4.73 eV, 4.81 eV, 4.68 eV)-the luminescence features indicated distinctive defect levels-affecting the electronic energy structure significantly. By increasing the Nb doping level from 0.0001 mol% to 0.1 mol%, the Fermi level (E-F) moves closer to the bottom of the conduction band. For the sample with Nb doping 0.5 mol%-no further improvement is noticed in the electronic properties. Finally, the energy band diagrams of four samples are given.

Automated summary

Systemic investigations were conducted to understand the structural, optical, and electrical characteristics of four niobium-doped beta-Ga2O3 crystals grown by the OFZ method. Different doping levels of niobium affected the bandgap energies and luminescence features, impacting the electronic energy structure. Increasing the Nb doping level led to the Fermi level moving closer to the bottom of the conduction band, but no further improvement in electronic properties was observed at 0.5 mol% Nb doping level.