Approaches toward chemically prepared multiple quantum well structures

摘要

An enhanced thermoelectric figure of merit, ZT, has been predicted for Bi_2Fe_3 in the form of 2-dimensional quantum wells. A new approach to making multiple quantum well (MQW) structures for thermoelectric applications utilizing a chemical intercalation technique is proposed and investigated. it is proposed that by starting from Li intercalated Bi_2Te_3 and Bi_2Se_3, the layers of these materials can be spearated by chemical means. Thelayers of Bi_2Te_3 or Bi_2S3_3 can the be restacked, by self-assembly, forming a non-periodic array of quantum wells. Thesechemically prepared MQWs are characterized by X-ray diffraction, SEM (scanning electron microsocpy) and TEM (transmission electron miroscopy) at various stages in the sample preparations to assess the degree to which the actual samples match the proposal. Expeirmental measurements of the Seebeck coefficient (S) and the electrical conductivity ( singma ) were performed over a range of temperatures for the initial bulk materials. It is found that some of the steps in the proposed fabrication have been achieved but still much improvement is needed before any practical thermoelectric 2D-system can be provided.