Doped InAs nanocrystals; A model system for doping effects in colloidal semiconductor nanocrystals - ICS84 The 84th Annual Meeting of the Israel Chemical Society

Lior Asor ¹ Durgesh Tripathi ² Gil Zaharoni ¹ Jing Liu ³ Anatoly I. Frenkel ³ Nir Tessler ² Uri Banin ¹

¹Institute of Chemistry and Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, Israel
²The Zisapel Nano-Electronics Center, Department of Electrical Engineering, Technion – Israel Institute of Technology, Haifa, Israel
³Department of Material Science and Chemical Engineering, Stony Brook University, Stony Brook, NY, USA

Development of electronic devices such as diodes, transistors, sensors, and others, requires the use of expensive top-down industrial processes involving high temperature conditions and rigid substrates. Printed Electronics (PE) offers a facile and cost-effective alternative approach for the fabrication of such devices that may be implemented on various types of substrates ranging from flexible substrates, to glass and metals. The fabrication of printed electronics devices by using inorganic colloidal semiconductor nanocrystals (NCs) as the active material, holds higher potential for demonstrating improved performance and stability over the use of organic semiconductors. However, the aspects of doping colloidal semiconductor nanocrystals still present many challenges and open questions about developing effective strategies for doping, structural characterization of the doped NCs and correlation with its electrical functionality.

In that sense, InAs nanocrystals serve as an interesting model system for doping effects in colloidal NCs and are promising candidates for such applications, due to extremely high electron mobility and the ability to tune the InAs NCs direct band gap by controlling the NCs size for optoelectronic applications. However, little is known about InAs NCs – based electronic devices relative to Cd- and Pb-based NCs and the ability to control the carrier type, concentration and mobility in InAs NCs films remains a great challenge.

In this work, we present the ability to control the carrier type in InAs NCs by the incorporation of Cd via a post-synthesis doping reaction leading to p-type doping. By preparing field effect transistors (FETs) we compared films made of Cd–doped InAs NCs, to films of undoped InAs NCs. Cd-doped transistors presented fundamentally different properties due to the switch in majority carrier type that is attributed solely to Cd incorporation.

In addition, structural analysis including X-ray absorption spectroscopy and X-ray diffraction was performed, suggesting that Cd passivates surface donor sites on the NC along with In substitution, giving rise to the observed p-type doping.