Aerosol-assisted Chemical Vapour deposition (AACVD) of Inorganic Functional Materials

Theme: Aerosol Technology
Start date: Cohort 1: 2019
Supervisors: Dr Andrew Johnson (Bath) and Dr Adam Squires (Bath)
This project will use aerosol assisted chemical vapour deposition (AA-CVD) to develop inorganic and hybrid semiconducting materials e.g. SnS, Sb2S3 and FeS2 by the in-situ decomposition of soluble molecular precursors. The project offers a combination of chemical synthesis and aerosol/materials characterisation
Abstract:
Continued success of the electronic and energy sectors is driven by technological advances in the semiconductor industry. In layered combination, electron donating (n-type) and electron accepting (p-type) semiconductor materials form heterojunctions, which are the bedrock of transistor and photovoltaic devices. The miniaturisation of such devices has prompted a recent shift away from classical silicon-based materials, of which thin films are challenging to fabricate. As an alternative, the capabilities of both organic polymers and metal-based materials have been investigated, with the latter being favoured for their durability. Consequently, the fabrication of intricate layered architectures comprising inorganic semiconductors is of growing importance. Aerosol-assisted chemical vapour deposition (AACVD) is a promising fabrication technique. Aerosolisation of precursor solutions mitigates the volatility required for typical chemical vapour deposition methods, broadening the range of possible deposition precursors available. 
It is proposed to survey the thermal properties of and thin films produced from, a series of metal chalcogenide molecular precursors for AACVD; thus to redress the relative lack in available precursors for formulation of inorganic p-type semiconductors. Initial attention will be focused upon the formulation of group 15chalcogenide systems (M2X3, M = As, Sb, Bi and X = S, Se, Te), which are currently underdeveloped. More specifically, it is proposed initially to examine group 15 molecular complexes with xanthate-derived ligands, the deposition mechanism of which has been pre-characterised. The work may expand to other metals, for example tin or zinc. The aim is to yield a series of precursor chemicals viable for commercial AACVD scale-up, to assist the construction of both constituents of an inorganic heterojunction. Future work can interrogate parameters controlling aerosol-mediated deposition, probing the influence of droplet size and solvent on film morphology.