Influence of heat treatments in H2 and Ar on the E1 center in β-Ga2O3

Abstract

     

We looked at the possibility of the defect level E1 in heat treated n-type bulk β-Ga2O3 in hydrogen

(H2) and argon (Ar) gases. The presence of hydrogen (H) doped β-Ga2O3 during H2 annealing at 900 °C has been verified via the use of Fourier transform-infrared spectroscopy. Studies using deep-level transient spectroscopy reveal that the addition of H increases the concentration of the E1 level, which contradicts the results seen in samples heat-treated in an Ar flow. Regardless of the presence or absence of a reverse-bias voltage, the E1 level does not change after heat treatments at 650 K. Possible causes of E1's flaw may be investigated using the hybrid-functional computations. We find three types of hydrogen-containing defect complexes that are consistent with E1 in terms of their charge-state transition levels. These include arrangements of singly hydrogenated Ga-O vacancies, shallow Ga-substitutional hydrogen-passivated donor impurities, and substitutional hydrogen at one of the triple coordinated O sites. The observed thermal stability of E1 is compatible with only the second kind of hydrogen binding energies.