Non-Chemical Carrier Addition to Antiferromagnetic Semiconductors

点击翻译按钮获取中文摘要

9411748 Kastner Large single crystals, about a centimeter cube in volume, of layered copper oxides grown at Massachusetts Institute of Technology will be used for non-chemical methods of adding charge carriers. Photoexcitation of electrons and holes will be studied using transient photoconductivity and photo-induced optical absorption. External electric fields will be applied in a field- effect-transistor geometry to add electrons or holes. Two compounds, previously studied using chemical doping and, which become superconducting when electrons and holes are added, respectively will be investigated. Also to be studied is a third compound which cannot be doped by other means. % % % % High temperature superconductivity results from chemical doping of oxide semiconductors to change the density of electrons in them. To understand the mechanism that leads to this interesting and potentially useful phenomenon one would like to introduce electrons without the disorder which is inherent in chemical doping. The proposed work will use large crystals of the copper oxides to explore two ways of doing this. In one, electrons will be added by exposure to light. In the other they will be added by an external electric field. ***