Hole-trapping-related transients in shallow n(+)-p junctions fabricated ina high-energy boron-implanted p well

This letter describes a transient phenomenon in the reverse hole current of large-area shallow n(+)-p-well junctions, giving rise to a hump at a speci fic reverse bias. This corresponds to a certain depletion depth in the retr ograde p well, which has been fabricated by a deep (200 keV) and a shallow (55 keV) boron ion implantation. No such a reverse hole current hump occurs for reference diodes, processed in p-type Czochralski substrates. The effe ct is also absent in large-perimeter p-well junctions, suggesting a correla tion with defects in the p-well region. The occurrence at a specific deplet ion depth indicates a nonuniform defect distribution, for example related t o the displacement damage created by the 200 keV B implantation. This idea is further supported by deep level transient spectroscopy results, which re veal the presence of a nonuniform density of hole traps, corresponding to a broad range of energy levels from about 0.3 to 0.5 eV above the valence ba nd. A discussion of the possible nature of the underlying defects is given. (C) 2001 American Institute of Physics.