Hydrothermally Grown Single-Crystalline Zinc Oxide; Characterization and Modification
2007 (English)In: MRS Proceedings Volume 1035 / 2007, Warrendale, PA, USA: Materials Research Society, 2007Conference paper (Other academic)
An overview of our recent results on characterization and modification of high-resistivity n-type bulk zinc oxide samples, grown by hydrothermal techniques, is given. Three specific topics are addressed; (i) the role of lithium (Li) as an electrically compensating impurity, (ii) extrinsic n-type doping by hydrogen implantation, and (iii) influence of annealing conditions on deep band emission. In (i), furnace annealing of as-grown samples at temperatures above ∼800 °C is shown to cause out-diffusion of residual Li impurities and concurrently, the resistivity decreases. After annealing at 1400 °C, a resistivity close to 10−1 Ωcm is obtained and the Li content is reduced from above 1017 cm−3 to the mid 1015 cm−3 range, providing evidence for the crucial role of Li as an electrically compensating impurity. For ion-implanted samples, vacancy clusters evolve during post-implant flash lamp annealing (20 ms duration) and these clusters appear to trap and deactivate Li with a resulting improvement of the n-type conductivity. However, these clusters have a limited stability and start to dissociate already after 1h at 900 °C, accompanied by a decrease in the conductivity. For topic (ii), n-type doping by hydrogen implantation is shown to enhance the conductivity by about 5 orders of magnitude already in the as-implanted state. Despite substantial loss of hydrogen, the conductivity remains stable, or even increases, after annealing up to ≥600 °C, and necessary conditions for doping by hydrogen are discussed. In (iii), the origin of the commonly observed deep band emission from monocrystalline zinc oxide is investigated using a concept of annealing as-grown samples in different atmospheres. A strong influence by the atmosphere and temperature is observed and the results can be interpreted in terms of dominant effects on the emission by vacancy-related defects.
Place, publisher, year, edition, pages
Warrendale, PA, USA: Materials Research Society, 2007.
, Materials Research Society Symposium Proceedings, ISSN 0272-9172
semiconducting; electrical properties; optical properties
National CategoryEngineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-41145DOI: 10.1557/PROC-1035-L04-01Local ID: 55265OAI: oai:DiVA.org:liu-41145DiVA: diva2:261995
MRS Fall Meeting, Boston, Massachusetts, USA, November 26-30, 2007