Size, composition, and doping effects on In(Ga)As nanowire/Si tunnel diodes probed by conductive atomic force microscopy

Tao Yang, Simon Hertenberger, Stefanie Morkötter, Gerhard Abstreiter, Gregor Koblmüller

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43 Scopus citations

Abstract

We investigate the effect of various parameters on the room-temperature interband tunneling characteristics of molecular beam epitaxy grown, intrinsically n-type In(Ga)As nanowires (NWs) on p-type silicon (Si) substrate using conductive atomic force microscopy. Large interband tunnel currents (>40 kA/cm2) and reduced breakdown voltages are obtained by increasing the p-type substrate doping level to >1 × 1019 cm-3. Current mapping under forward bias reveals a bimodal distribution of NW/Si hetero-junction tunnel diodes exhibiting either negative differential resistance (NDR, Esaki diode) or high excess currents (without NDR). By downscaling the NW diameter from ∼90 nm to ∼25 nm, peak-to-valley current ratios in NDR-type diodes increase and saturate with maximum values of ∼3. Increasing Ga content (xGa up to ∼0.1) in In-rich ternary InGaAs NWs preserves the NDR behavior, while the peak current shifts to lower voltages due to reduced Fermi energy in InGaAs. Band profile calculations were performed to further support these findings.

Original languageEnglish
Article number233102
JournalApplied Physics Letters
Volume101
Issue number23
DOIs
StatePublished - 3 Dec 2012

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