MSE Seminar Series: Babak Nikoobakht
Friday, February 17, 2012
1:00 p.m.-2:00 p.m.
Room 2110 Chemical and Nuclear Engineering Bldg.
301 405 5240
Challenges In 1D Growth of Zinc Oxide Nanocrystals and Their Device Integration
Surface and Interface Research Group
With more than a decade of intensive work and great progress on one dimensional (1D) nanocrystals, there are still major barriers in their integration into devices for real applications. Two key issues are variation in properties of nanowires i an ensemble and control over their large scale order. In studying their properties, measurements have been typically carried out on individual nanowires; statistical measurements on large nanowire populations are lacked and the extent of property variation is not well studied. In the case of zinc oxide and other semiconductors with applications in opto-electronic devices such as light sources, the electro-optical results show a considerable fluctuation over the ensemble that is due to the type and distribution of the defects. Another issue that will be discussed is progress in precision control of the hierarchy of nanowires. There is a growing need for discovering alternative paradigms for low cost device miniaturization as top-down approaches are becoming more expensive. For nanowires, the basic question is how millions of them can be interfaced in very specific locations and with specific functions. In this presentation I will show how the two key issues above can be closely related to the more fundamental issue of controlled growth of nanowires. To this end, a surface directed nanocrystal growth method will be discussed, which is similar to the vapor-liquid-solid process but offers some new benefits. Results will also be presented on extension of this method to other II-VI and III-V semiconductors, their crystal structure as well as their growth direction engineering.