RESIDUAL ION DAMAGE IN GAAS-C PREPARED BY COMBINED ION-BEAM AND MOLECULAR-BEAM EPITAXY

Ion-induced damage in the films grown by low-energy (30-30 000 eV) ion -beam doping method was investigated using the minority-carrier lifeti me and temperature-dependent Hall-effect measurements, Minority-carrie r lifetime measurement using scanning tunneling microscope stimulated time-resolved luminescence (STM-L) demonstrated the presence of residu al ion damage in as-grown samples at C+-ion acceleration energy EC+ = 240 and 350 eV, and annealed ones at EC+ = 5, 10 and 30 keV, For EC+ = 30 eV, no ion damage was observed in as-grown condition, For EC+ grea ter than or equal to 5 keV, ion damage remains even after high-tempera ture annealing and degrades the activation of C atoms. In the temperat ure-dependent Hall-effect measurements, samples with Ec = 240 and 350 eV showed unusual characteristics in net hole carrier concentration (\ N-A - N-D\) with decreasing temperature. For EC+ = 10 and 30 keV, \N-A - N-D\ in lower temperature regions indicates higher values than that obtained at room temperature, It was suggested that the conduction me chanisms of these two specimens are significantly affected by impurity conduction mainly due to ion damage.