Shallow donor formation in hydrogen-implanted silicon

Formation of shallow donors has been studied in 100-keV hydrogen-implanted n-type silicon with a dose of 1x10(15) cm(-2). Annealing experiments are mode in the temperature range 100 to 800 degrees C. Gold Schottky contacts are fabricated on these samples to obtain carrier concentration profiles. The hydrogen profiles are measured by secondary ion mass spectroscopy. In the annealing temperature range 350 to 450 degrees C, an increase of die carrier concentration is observed near the surface region with almost flat depth profiles. The well-known hydrogen-related donors (Ist shallow donors) disappear around 400 degrees C, while shallow donors (2nd shallow donors)observed here decrease above 500 degrees C. Hydrogen profiles show almost no change in the 2nd donor formation temperatures, although hydrogen starts to outdiffuse at 250 degrees C. This indicates that the 2nd shallow donors are related to hydrogen atoms and to implantation-induced damage. The implantation-induced defects trap diffusing hydrogen atoms, which leads to the formation of tile 2nd shallow donors.