Argonne National Laboratory

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Band Gap Engineering in Ternary Semiconductors

Materials Science Seminar
Rita John, University of Madras, India
April 3, 2014 2:00PM to 3:00PM
Building 223, Room S105
Semiconductors play a vital role for the development of modern technology. The most important parameter that decides the area of application of any semiconductor is its band gap (Eg). Interestingly, Eg can be engineered at the microscopic level through the crystal structural parameters. The effects studied as band gap anomalies in some of the ternary pnictides, ABC2 (A=Cd; B=Si,Ge,Sn; C=P,As) using theoretical prescription will be presented. These compounds exhibit transitions in the nature of bonding.

Band gaps change from indirect to direct in addition to the changes in the values of Eg, while most of them exhibit pseudogap nature. Such changes have direct consequence on their optical properties with degenerate states being lifted leading to crystal field splitting. The Eg is engineered as a function of the crystal structural parameters, the anion position parameter (u) and tetragonal compression parameter (n) through effective alloying. The impact of u and η on the nature of bonding is analyzed. The correlations that exist among the structural and mechanical properties in these compounds will also be presented. This theoretical investigation is a valuable tool for experimentalists to make tailor made compounds to suit a particular application.