Effect of unintentional nitrogen incorporation on n-type doping of β-Ga2O3 grown by molecular beam epitaxy

In this study, the effect of unintentional nitrogen incorporation on n-type doping of β-Ga2O3 films grown by plasma-assisted molecular beam epitaxy has been demonstrated. The nitrogen atoms, with a concentration as high as 2×1019 cm-3, are confirmed to originate from the decomposition of the pyrolytic boron nitride (PBN) crucible in the plasma source. These atoms act as acceptors in β-Ga2O3 and severely compensate the Si-donors, thus, hindering the generation of n-type β-Ga2O3. Instead, a quartz (SiO2) crucible free of nitrogen atom can overcome this issue, leading to the successful generation of n-type β-Ga2O3 with tunable electron concentration in the range 5.0×1016-2.6×1019 cm-3.