Identification of critical buffer traps in Si δ-doped β-Ga₂O₃ MESFETs

Two buffer traps at EC-0.7 eV and EC-0.8 eV have been individually identified as causing threshold voltage and on-resistance instabilities in β-Ga2O3 Si ∂-doped transistors grown by plasma-assisted molecular beam epitaxy (PAMBE) on semi-insulating Fe doped β-Ga2O3 substrates. The instabilities are characterized using double-pulsed current-voltage and isothermal constant drain current deep level transient spectroscopy. The defect spectra are compared between transistors grown using two different unintentionally doped buffer layer thicknesses of 100 nm and 600 nm. The EC-0.8 eV trap was not seen using the thicker buffer and is shown to correlate with the presence of residual Fe in thePAMBE buffer layer. The EC-0.7 eV trap was unchanged in concentration and is revealed as the dominating source of the threshold voltage instability. This trap is consistent with the characteristics of a previously reported intrinsic point defect [Ingebrigtsen et al., APL Mater. 7, 022510 (2019)]. The EC-0.7 eV trap is responsible for ∼70% of the total threshold voltage shift in the 100 nm thick buffer transistor and 100% in the 600 nm thick buffer transistor, which indicates growth optimization is needed to improve β-Ga2O3 transistor stability.Two buffer traps at EC-0.7 eV and EC-0.8 eV have been individually identified as causing threshold voltage and on-resistance instabilities in β-Ga2O3 Si ∂-doped transistors grown by plasma-assisted molecular beam epitaxy (PAMBE) on semi-insulating Fe doped β-Ga2O3 substrates. The instabilities are characterized using double-pulsed current-voltage and isothermal constant drain current deep level transient spectroscopy. The defect spectra are compared between transistors grown using two different unintentionally doped buffer layer thicknesses of 100 nm and 600 nm. The EC-0.8 eV trap was not seen using the thicker buffer and is shown to correlate with the presence of residual Fe in thePAMBE buffer layer. The EC-0.7 eV trap was unchanged in concentration and is revealed as the dominating source of the threshold voltage instability. This trap is consistent with the characteristics of a previously reported intrinsic point defect [Ingebrigtsen et al., APL Mater. 7, 022510 (2019)]. The EC-0.7 eV trap is respons...