Comparative passivation effects of self-assembled mono- and multilayers on GaAs junction field effect transistors

Kangho Lee, Purdue University
Gang Lu, Northwestern University
Antonio Facchetti, Northwestern University
David B. Janes, Purdue University
Tobin J. Marks, Northwestern University

Abstract

Control of semiconductor interface state density with molecular passivation is essential for developing conduction- based biosensors. In this study, GaAs junction field effect transistors ( JFETs ) are fabricated and characterized before and after passivation of the GaAs surface with self- assembled mono- and multilayers. The JFETs functionalized with 1- octadecanethiol monolayers and two types of self- assembled organic nanodielectric ( SAND ) multilayers exhibit significantly different threshold voltage ( V-th ) and subthreshold slope ( S-sub ) characteristics versus the unpassivated devices and provide useful information on the quality of the passivation. Two- dimensional device simulations quantify the effective density of fixed surface charges and interfacial traps and argue for the importance of the type- III SAND ionic charges in enhancing GaAs JFET response characteristics.