Institute of High Pressure Physics

Doping Gallium Nitride (GaN) with beryllium has attracted much attention due to its potential applications in electronics and optoelectronics. Early studies suggested Be acceptors to have a lower ionization energy than the commonly used magnesium (Mg). However, previous attempts mostly lead to fabrication of semi-insulating material, due to a self-compensation effect – the tendency of Be atoms to occupy interstitial positions in GaN lattice (instead of substitution ones), forming competing donor defects.

Recent studies indicate that Be may have a more complex dual nature: acting as a shallow acceptor or as a deeper polaronic acceptor. Research carried out by the Institute of High Pressure Physics PAS, in collaboration with Virginia Commonwealth University and the University at Albany (USA), published in the Journal of Applied Physics, confirmed this hypothesis.

Hall effect measurements on GaN:Be layers showed p-type conductivity without overcompensation by donors, with an acceptor activation energy of ~0.40 eV. These results suggest that effective p-type doping of GaN with Be is more challenging than previously expected.

The research was funded by the National Science Centre, Poland (grant no. 2020/37/B/ST5/03746).

More details can be found in the following publication: M. Zając et al., Journal of Applied Physics 138, 095705 (2025). https://doi.org/10.1063/5.0283055.

Experimental pT^-3/2 vs inverse temperature dependence of GaN:Be epitaxial layers of various Be content. Solid lines represent fits yielding deep Be acceptor level at T=0.