Non-Chemical Carrier Addition to Antiferromagnetic Semiconductors

麻省理工学院培育的层状氧化铜大单晶，体积约为立方厘米，将用于非化学方法添加载流子。利用瞬态光电导率和光致光吸收来研究电子和空穴的光激发。在场效应晶体管的几何结构中，将施加外部电场以增加电子或空穴。之前使用化学掺杂和添加电子和空穴研究过的两种化合物将分别被研究。还需要研究一种不能用其他方法掺杂的第三种化合物。% % % %高温超导性是由化学掺杂氧化物半导体改变其电子密度而产生的。为了理解导致这种有趣和潜在有用现象的机制，我们希望引入没有化学掺杂固有的无序的电子。提出的工作将使用铜氧化物的大晶体来探索实现这一目标的两种方法。其中一种是通过暴露在光线下增加电子。在另一种情况下，它们会被一个外电场加起来。＊＊＊

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. ***