In-situ resistivity and Hall effect studies of persistent photoconductivity in oxygen-depleted YBa{sub 2}Cu{sub 3}O{sub x}
- Univ. Wien (Austria). Inst. fuer Festkoerperphysik
- Univ. of Rochester, NY (United States)
The authors report on in-situ studies of the resistivity and the Hall effect in partially oxygen-depleted, metallic YBa{sub 2}Cu{sub 3}O{sub x} (YBCO) thin films during illumination with white light. The measurements were performed at temperatures of 100 K, 200 K, and 290 K and showed that the resistivity as well as the Hall coefficient decreased as a function of the illumination time. The photo-induced reduction of both quantities was largest at 290 K. Evaluation of the results of the Hall effect measurements within a simple one-band model shows that both the carrier mobility and the carrier concentration are enhanced by photodoping at 100 K and 200 K, with the enhancement of the carrier concentration dominating. At 290 K, however, the mobility decreases at large illumination times, whereas the carrier concentration increases substantially, over-compensating for the loss of mobility. From the qualitatively different time dependencies of the carrier mobility and the carrier concentration, they conclude that two co-existing mechanisms contribute to photodoping: the first mechanism is related to a change of the electronic structure and is tentatively attributed to photo-assisted oxygen ordering. The second mechanism resembles the photogeneration of carriers in semiconductors and is ascribed to a photo-induced charge transfer. At 290 K, only the charge transfer process drives photodoping, whereas oxygen ordering seems to be hampered by thermal disordering. Additional evidence for the co-existence of the two persistent photoconductivity mechanisms is derived from measurements of the spectral efficiency of photodoping at 253 K. They observe a finite photodoping effect at photon energies above and below the charge transfer gap of YBCO. Above the gap energy ({approx} 1.6 eV), however, the efficiency of photodoping increases remarkably. The conclusion is that two mechanisms contribute to photodoping in metallic YBCO.
- OSTI ID:
- 549856
- Report Number(s):
- CONF-960163-; ISBN 0-8194-2070-0; TRN: 98:000478
- Resource Relation:
- Conference: Photonics West `96: conference on quantum well and superlattice physics VI, San Jose, CA (United States), 27 Jan - 2 Feb 1996; Other Information: PBD: 1996; Related Information: Is Part Of Spectroscopic studies of superconductors. Part B: Tunneling, photoelectron, and other spectra; Bozovic, I.; Marel, D. van der [eds.]; PB: 370 p.; Proceedings/SPIE, Volume 2696
- Country of Publication:
- United States
- Language:
- English
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