Very low densities of localized states at the Fermi level in hydrogenated polymorphous silicon from capacitance and space-charge-limited current measurements

The density of states at the Fermi level N(E-F) has been measured on hydrog enated polymorphous (pm-Si:H) silicon samples using both capacitance measur ements on Schottky barriers and space-charge-limited current measurements o n n(+)/i/n(+) structures. From both techniques, N(E-F) values of 7-8 x 10(1 4) cm(-3) eV(-1) have been obtained, which is significantly lower than repo rted in the literature for hydrogenated amorphous silicon (a-Si:H). Such va lues demonstrate that pm-Si:H is a very low defect density material which s hould be able to replace a-Si:H in the field of applications like photovolt aics. (C) 1999 American Institute of Physics. [S0003-6951(99)02747-3].