Density of states in the gap of amorphous semiconductors determined from modulated photocurrent measurements in the recombination regime

R.R. KOROPECKI; J.A. SCHMIDT; R. D. ARCE

JOURNAL OF APPLIED PHYSICS

AIP

Lugar: New York; Año: 2002 vol. 91 p. 8965 - 8969

0021-8979

An experimental technique to study the energy profile of localized states in the gap of amorphoussemiconductors is proposed. The method is based on the relationship between the recombinationlifetime and the density of states ~DOS! at the quasi-Fermi level for trapped carriers. We use themodulated photocurrent experiment in the recombination-limited regime as a convenient method tomeasure the recombination lifetime. Measurements performed as a function of temperature allowthe DOS above the Fermi energy to be determined. The accuracy and limitations of the method arestudied by means of computer simulations. The experimental technique is applied to obtain thedensity of defect states of a hydrogenated amorphous silicon sample.