PhD: Francesco Salutari

Directors:

ICREA Prof. Jordi Arbiol, Group Leader of the Advanced Electron Nanoscopy group at Institut Català de Nanociència i Nanotecnologia (ICN2)

Prof Maria Chiara Spadaro, Visiting Professor at ICN2 

Short Abstract: This thesis presents a detailed TEM study of earth-abundant materials, primarily Zn₃P₂ and SnSe, for photovoltaic and thermoelectric applications, respectively. We begin by studying Zn₃P₂ grown epitaxially on InP substrates by metal-organic vapor-phase epitaxy (MOVPE), both in the form of nanowires and thin films. Results from structural and compositional characterization position MOVPE as a viable alternative to molecular beam epitaxy (MBE) for the scalable production of Zn₃P₂-based photovoltaic devices. Next, we address the structural characterization of extended intrinsic defects across a broad set of MBE- and MOCVD-grown Zn₃P₂ samples. We show that defect-free material is unattainable through conventional growth, albeit DFT calculations evidence an almost unperturbed optoelectronic response in relation to intrinsic defects. Finally, we investigate the dielectric response and band gap of polycrystalline SnSe doped with Na for thermoelectric applications via valence EELS. We find band gap narrowing at grain boundaries in the presence of Na.

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