Nuclear spin relaxation phenomena in amorphous semiconductors
1983; Elsevier BV; Volume: 59-60; Linguagem: Inglês
10.1016/0022-3093(83)90537-9
ISSN1873-4812
Autores Tópico(s)Solid-state spectroscopy and crystallography
ResumoRecent nuclear magnetic resonance (NMR) measurements of nuclear spin relaxation phenomena in amorphous semiconductors are discussed using examples from several amorphous systems. Studies of nuclear spin-lattice relaxation times (T1) and spin-spin relaxation times (T2) are useful probes of several important phenomena in amorphous semiconductors. For example, the anomalous temperature dependences (approximately Tβ, 1 ⩽ β ⩽ 2) of the spin-lattice relaxation rates in several chalcogenide glasses have been attributed to the presence of disorder modes in these amorphous solids. In some cases the dominant contributions to T1 are made by defects or impurities, such as trapped molecular hydrogen or "dangling bonds" in a-Si:H. Other localized electronic states can also play important roles in spin lattice relaxation processes. Such states include optically induced ESR centers or optically excited band tail states. Spin-spin relaxation rates are useful probes of dipolar interactions in amorphous semiconductors. From these measurements one can infer such structural details as clustering of hydrogen in a-Si:H and intermediate-range ordering in As2S3 and As3Se3.
Referência(s)