Non-Chemical Carrier Addition to Antiferromagnetic Semiconductors

小行星9411748 在马萨诸塞州学院生长的层状氧化铜的大单晶体，体积约为一立方厘米，将用于添加电荷载体的非化学方法。 电子和空穴的光激发将使用瞬态光电导和光致光吸收来研究。 将在场效应晶体管几何结构中施加外部电场以添加电子或空穴。 两种化合物，以前研究使用化学掺杂和，成为超导时，电子和空穴添加，将分别进行研究。 还需要研究的是不能通过其他方式掺杂的第三种化合物。 % % % % 高温超导性是通过对氧化物半导体进行化学掺杂来改变其中的电子密度而产生的。 为了理解导致这种有趣且潜在有用的现象的机制，人们希望引入没有化学掺杂中固有的无序的电子。 拟议的工作将使用氧化铜的大晶体来探索两种方法。 其中一种方法是通过暴露在光下来增加电子。 在另一种情况下，它们将通过外部电场添加。 ***

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. ***