Accurate carrier profiling of n-type GaAs junctions

Abstract

As CMOS is approaching the 22 nm node, the importance of high-mobility materials such as Ge and GaAs is rapidly increasing. For the timely development of these new technologies accurate dopant and carrier-profiling solutions for source-drain extensions with these materials are required. Identical n-type-doped (Si, Se) layers on same and opposite type medium-doped layers on S.I. GaAs substrates will be investigated, with layer thicknesses ranging from 200 down to 50 nm and doping concentration levels up to 1e20 at/cm(3). In this work, secondary ion mass spectrometry will be used for dopant profiling. For GaAs carrier profiling, conventional spreading resistance probe, as commonly used in Si-CMOS, fails. Hence, reliable alternatives need to be found for characterizing these high-low structures. Techniques to be discussed range from the more conventional approaches such as Hall or electrochemical capacitance-voltage (performed by different laboratories), over micro-Raman spectroscopy and photoluminescence along a beveled surface, up to more advanced approaches using scanning spreading resistance microscopy. (C) 2008 Elsevier Ltd. All rights reserved.