**Structural and Optical Properties of Luminescent Copper(I) Chloride Thin Films Deposited by Sequentially Pulsed Chemical Vapour Deposition**

**Richard Krumpolec 1, Tomáš Homola 1, David C. Cameron 1,\*, Josef Humlícek ˇ 2, Ondˇrej Caha 2, Karla Kuldová 3, Raul Zazpe 4,5, Jan Pˇrikryl <sup>4</sup> and Jan M. Macak 4,5**


Received: 31 August 2018; Accepted: 15 October 2018; Published: 18 October 2018

**Abstract:** Sequentially pulsed chemical vapour deposition was used to successfully deposit thin nanocrystalline films of copper(I) chloride using an atomic layer deposition system in order to investigate their application to UV optoelectronics. The films were deposited at 125 ◦C using [Bis(trimethylsilyl)acetylene](hexafluoroacetylacetonato)copper(I) as a Cu precursor and pyridine hydrochloride as a new Cl precursor. The films were analysed by XRD, X-ray photoelectron spectroscopy (XPS), SEM, photoluminescence, and spectroscopic reflectance. Capping layers of aluminium oxide were deposited in situ by ALD (atomic layer deposition) to avoid environmental degradation. The film adopted a polycrystalline zinc blende-structure. The main contaminants were found to be organic materials from the precursor. Photoluminescence showed the characteristic free and bound exciton emissions from CuCl and the characteristic exciton absorption peaks could also be detected by reflectance measurements.

**Keywords:** vapour deposition; copper chloride; characterization; optical properties; XPS; crystal structure
