  Doped heavy metal-free III-V semiconductor nanocrystal quantum dots are of
great interest both from the fundamental aspects of doping in highly confined
structures, and from the applicative side of utilizing such building blocks in
the fabrication of p-n homojunction devices. InAs nanocrystals, that are of
particular relevance for short wave IR detection and emission applications,
manifest heavy n-type character poising a challenge for their transition to
p-type behavior. We present p-type doping of InAs nanocrystals with Zn-enabling
control over the charge carrier type in InAs QDs field effect transistors. The
post-synthesis doping reaction mechanism is studied for Zn precursors with
varying reactivity. Successful p-type doping was achieved by the more reactive
precursor, diethylzinc. Substitutional doping by Zn2+ replacing In3+ is
established by X-ray absorption spectroscopy analysis. Furthermore, enhanced
near IR photoluminescence is observed due to surface passivation by Zn as
indicated from elemental mapping utilizing high resolution electron microscopy
corroborated by X-ray photoelectron spectroscopy study. The demonstrated
ability to control the carrier type, along with the improved emission
characteristics, paves the way towards fabrication of optoelectronic devices
active in the short wave IR region utilizing heavy-metal free nanocrystal
building blocks.
