Improving electrical characteristics of W/HfO(2)/In(0.53)Ga(0.47)As gate stacks by altering deposition techniques

Abstract

The effects of controlling InGaAs substrate temperature during electron beam deposition of HfO(2) on electrical characteristics of W/HfO(2)/n-In(0.53)Ga(0.47)As capacitors are investigated. It is found that by depositing a thin HfO(2) layer at the interface when substrate temperature is raised to 300 degrees C, frequency dispersion at depletion and accumulation conditions is reduced and interface state density is lowered regardless of the HfO(2) thickness. Cross-sectional transmission electron microscopy images have revealed that the formation of mesoscopic voids in the InGaAs substrate near the interface is suppressed with HfO(2)deposition at 300 degrees C at the interface. A band diagram with an additional bulk trap energy level has been proposed to explain the frequency dispersion and conductance peaks at accumulation condition. (c) 2011 Elsevier B.V. All rights reserved.