Hydrogen-induced platelets in disordered silicon

It is demonstrated that hydrogen passivation of polycrystalline silicon(poly-Si) causes the formation of hydrogen stabilized platelets. These extended defects appear within 1000 Angstrom of the sample surface and are predominantly oriented along (111) crystallographic planes. Nominally undoped and phosphorous doped poly-Si ([P]=10(17) cm(-3)) show platelet concentrations of approximate to 5x10(15) cm(-3) and 1.5x10(16) cm(-3), respectively. An estimate of the number of H atoms accommodated in platelets by forming Si-H bonds is consistent with the hydrogen concentration in the surface layer measured by SIMS. Platelets were not observed in the grain boundary regions. This is due to two effects: (I) The presence of a depletion layer at grain boundaries causing hydrogen to migrate in the positive charge state which is unfavorable for the platelet formation; (ii) Platelet nucleation is surpressed due to the presence of a high concentration of hydrogen trapping sites at grain boundaries. Copyright (C) 1996 Published by Elsevier Science Ltd