Electrical and optical properties of beryllium-implanted Mg-doped GaN

Abstract

We investigated the electrical and optical characteristics of beryllium implanted Mg-doped GaN materials. The Mg-doped GaN samples were grown by metalorganic chemical vapor deposition system and implanted with Be ions at two different energies of 50 and 150 keV and two different doses of about 10(13) and 10(14) cm(-2). The implanted samples were subsequently rapidly thermal annealed at 900, 1000, and 1100 degreesC for various periods. The annealed samples showed an increase of hole concentration by three orders of magnitude from nonimplanted value of 5.5x10(16) to 8.1x10(19) cm(-3) as obtained by Hall measurement. The high hole concentration samples also showed low specific resistance ohmic contact of about 10(-3) Omega cm(2) and 10(-6) Omega cm(2) using Ni/Au and Ni/Pd/Au metallization, respectively, without any further annealing process. It is also found from the temperature dependent photoluminescence that the activation energy of Mg dopants of the Be implanted samples has an estimated value of about 170 meV, which is nearly 30% lower than the as-grown samples of about 250 meV. The crystal quality and surface morphology of the Be implanted samples measured by x-ray diffraction and atomic force microscopy show no obvious degradation in the crystal quality and surface morphology. (C) 2002 American Institute of Physics.