Changes induced in electrical properties and deep level spectra of p‐AlGaN films by treatment in hydrogen plasma and by proton implantation

Abstract

The influence of hydrogen plasma treatment (250 °C, 0.5 h) and of proton implantation (proton energy of 200 keV, doses between 1012 and 1015 cm–2) on electrical properties of p-AlGaN films were studied. Hydrogen plasma treatment leads to substantial (more than an order of magnitude) decrease of the hole concentration in the surface layer. The dominant deep traps observed in current deep level transient spectroscopy were the Mg-related hole traps with activation energy of 0.17 eV and 0.19 eV. The concentration of both traps was strongly decreased after the hydrogen plasma treatment. At the same time the MCL intensity in the bandedge wavelength region was greatly increased. The results are explained by partial hydrogen passivation of Mg acceptors and of deep centers responsible for non-radiative recombination. Proton implantation was found to lead to a strong decrease of hole concentration, to a decrease in the intensity of the bandedge MCL signal and to a strong suppression of the signal from the hole traps with activation energy of 0.17 eV–0.19 eV. However, no new prominent deep centers were detected in deep level spectra after the implantation. It is suggested that the main centers responsible for the increased compensation of the layers are located in the upper part of the bandgap. Possible interplay between the hydrogen passivation of deep defects and introduction of new defects due to radiation and possibly due to hydrogen interaction with primary radiation defects will be discussed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)