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Becker, Jonathan; Hill, Megan O.; Sonner, Max; Treu, Julian; Doeblinger, Markus; Hirler, Alexander; Riedl, Hubert; Finley, Jonathan J.; Lauhon, Lincoln; Koblmüller, Gregor (2018): Correlated Chemical and Electrically Active Dopant Analysis in Catalyst-Free Si-Doped InAs Nanowires. In: ACS Nano, Vol. 12, No. 2: pp. 1603-1610
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Abstract

Direct correlations between dopant incorporation, distribution, and their electrical activity in semiconductor nanowires (NW) are difficult to access and require a combination of advanced nanometrology methods. Here, we present a comprehensive investigation of the chemical and electrically active dopant concentrations in n-type Si-doped InAs NW grown by catalyst-free molecular beam epitaxy using various complementary techniques. N-type carrier concentrations are determined by Seebeck effect measurements and four-terminal NW field-effect transistor characterization and compared with the Si dopant distribution analyzed by local electrode atom probe tomography. With increased dopant supply, a distinct saturation of the free carrier concentration is observed in the mid-10(18) cm(-3) range. This behavior coincides with the incorporated Si dopant concentrations in the bulk part of the NW, suggesting the absence of compensation effects. Importantly, excess Si dopants with very high concentrations (>10(20) cm(-3)) segregate at the NW sidewall surfaces, which confirms recent first-principles calculations and results in modifications of the surface electronic properties that are sensitively probed by field-effect measurements. These findings are expected to be relevant also for doping studies of other noncatalytic III-V NW systems.