Optical Emission Study of the Energy Levels of Ga-VACANCY/HYDROGEN Complexes in N and P-TYPE GaAs

Abstract

ABSTRACTThe formation of Ga-vacancy/hydrogen complexes in GaAs has been detected via photoluminescence measurements. Different degrees of hydrogénation can be achieved by low-energy H- or D-ion irradiation from a Kaufman source. The volume incorporation, for equal treatment, is dependent upon the density of impurities and defects where H can bind. In originally p-type MBE-GaAs, prolonged hydrogen treatments lead to the appearance of three emission structures in the range 1.15–1.34 eV. The results are explained in terms of transitions to different states of charge of gallium vacancies trapping one or more H-atoms, the activity of the individual states being dependent upon the H-dose and the nature of the laser excitation. The model is supported by comparison with the changes in the Ga-vacancy/donor emission band in degenerate n-type samples, as it evolves, from the virgin condition, through hydrogenation. The present observation provides also valid support to the creation, in p-type material, of a semi-shallow donor associated to H trapped along the As-Ga bond, in the immediate neighborhood of the gallium vacancy.