GaAsN alloys belong to a class of semiconductors with fascinating physical properties. Indeed, a small amount of nitrogen incorporation in GaAs leads to a counterintuitive and large band-gap reduction, and to an unexpected sudden increase in the effective mass of electrons. Even more surprisingly, both electronic and structural changes can be reversed fully and in a tunable manner by hydrogen incorporation. In this paper, we combine x-ray absorption spectroscopy at the nitrogen edge with ab initio simulations to investigate the atomic geometry of N-H complexes in hydrogenated GaAsN. In this way, we provide experimental evidence that dihydrogen-nitrogen complexes with C2v symmetry are the most abundant species in hydrogenated GaAsN. This finding contradicts previous predictions of “in-line” N-H2 * complexes as the predominant species, and accounts for recent infrared absorption experiments.
A new nitrogen-hydrogen complex in GaAsN revealed by X ray absorption spectroscopy / G. Ciatto; F. Boscherini; A. Amore Bonapasta; F. Filippone; A. Polimeni; M. Capizzi. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - STAMPA. - 71:(2005), pp. 201301-1-201301-4. [10.1103/PhysRevB.71.201301]
A new nitrogen-hydrogen complex in GaAsN revealed by X ray absorption spectroscopy
BOSCHERINI, FEDERICO;
2005
Abstract
GaAsN alloys belong to a class of semiconductors with fascinating physical properties. Indeed, a small amount of nitrogen incorporation in GaAs leads to a counterintuitive and large band-gap reduction, and to an unexpected sudden increase in the effective mass of electrons. Even more surprisingly, both electronic and structural changes can be reversed fully and in a tunable manner by hydrogen incorporation. In this paper, we combine x-ray absorption spectroscopy at the nitrogen edge with ab initio simulations to investigate the atomic geometry of N-H complexes in hydrogenated GaAsN. In this way, we provide experimental evidence that dihydrogen-nitrogen complexes with C2v symmetry are the most abundant species in hydrogenated GaAsN. This finding contradicts previous predictions of “in-line” N-H2 * complexes as the predominant species, and accounts for recent infrared absorption experiments.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.