Prospect of cobalt-mix-tetraethoxysilane method on localized lateral growth of carbon nanotubes for both p- and n-type field effect transistors

Abstract

To apply carbon nanotubes (CNTs) to nanoelectronics, researchers must effectively control the placement and manipulation of massive numbers of CNTs. In this work, we demonstrate a precise growth of single-walled carbon nanotubes (SWNT) on preassigned locations with only cobalt as catalyst. This is in contrast to the laborious and time-consuming physical manipulation of numerous nanotubes one at a time used in the conventional approach. Laterally grown CNTs were accomplished in preassigned areas using an integrated circuit compatible process in this study. In order to synthesize SWNT as the channel of a field effect transistor (FET), the cobalt-mix-tetraethoxysilane (CMT) solution and catalytic chemical vapor deposition were used. The CMT solution has the unique property of well dispersing the cobalt catalyst and uniformly embedding it in predetermined locations after the CMT solution has solidified. Our results show that laterally grown bundled-CNTs could be formed in atmospheric chemical vapor deposit ion with ethanol, by properly controlling the temperature of process, the process time, and the hydrogen reduction time. Since our bundled-CNTs were exposed to the air, all the as-grown CNT-FETs we manufactured exhibit p-type characteristics. Furthermore, we also demonstrate air-stable n-type CNT-FETs successfully without resorting to any additional and complicated annealing process by simply depositing a silicon nitride film on the as-grown p-type devices by plasma enhanced (PECVD) at 390 degrees C. The use of prepatterned catalyst islands, CVD method, and flexibility of simultaneously manufacturing both n- and p-type CNT-FETs may open a new era for applications of CNT-based nanoelectronics. (c) 2006 American Vacuum Society.