# Thin CdTe Layers Deposited by a Chamberless Inline Process using MOCVD, Simulation and Experiment
## 5 Conclusions  
Deposition of CdTe layers using a chamberless inline MOCVD process at atmospheric pressure was investigated. The substrate coverage, layer thickness and material utilisation were studied as a function of deposition parameters in both static and dynamic modes. It was shown that the deposition profile was dependent on the active exhaust parameters where the best substrate coverage was obtained using condition S-1. However, the S-4 condition yielded a 12% increase in material utilisation (Figure 7), having the potential to reach \(\sim\)67% in material utilisation. The study also examined mass transport limited and kinetic regimes with temperatures ranging from 305 \({}^{\circ}\)C to 430 \({}^{\circ}\)C. It was shown that material utilisation of 60% could be achieved with the potential to reach \(\sim\)70%. Material utilisation was strongly affected by the deposition temperature and plume control. The activation energy was found to be 59.62 kJ/mol, in reasonable agreement with previously reported values obtained using MOCVD of CdTe for the same precursors but in closed chambers. The numerical CFD modelling correlated well with experimental data regarding the deposition profiles, film thickness and the efficiency of precursor usage. The CFD simulation of CdTe might, therefore, facilitate the control and optimisation in the scaling up of the chamberless inline process (CIP) for thin film deposition.  
From the results presented here, it was also notable that the CIP could improve material utilisation for CdTe deposition compared with closed chamber MOCVD batch processes. The scalability and high material utilisation efficiency of CIP offered an alternative process technology for high throughput fabrication of thin-film PV modules.  
Figure 10: Experimental and numerical comparison of material utilisation as a function of \(T_{s}\) for (**a**) \(F_{total}=0.5\) L/min and (**b**) \(F_{total}=1.0\) L/min.  
**Author Contributions:** Conceptualisation, S.M., V.B. and S.J.C.I.; methodology, G.K.; software, S.M. and X.Y.; validation, S.M.; formal analysis, G.K., V.B., D.L., S.J.C.I. and X.Y.; investigation, S.M., G.K., V.B., D.L., S.J.C.I. and X.Y.; writing--original draft preparation, S.M. and Y.V.; writing--review and editing, S.M. and Y.V.; visualisation, G.K.; supervision, V.B., D.L., S.J.C.I., X.Y. and Y.V. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by the European Regional Development Fund through the Low Carbon Research Institute Programme (WEFO-80366) for the Solar Photovoltaic Academic Research Consortium (SPARC) Cymru project and by the European Social Fund project (case ID 80300) for a Knowledge Economy Skills Scholarship (KESS).  
**Acknowledgments:** The authors would like to thank ESF and MD [PERSON] from Scanvel Ltd. for funding the Knowledge Economy Skills Scholarship (KESS) and the Low Carbon Research Institute (LCRI) for funding the SPARC project. [PERSON], from NSG Pilkington, is also thanked for supplying the TEC glass for the SPARC project and Design Engineer [PERSON] from Scanvel Ltd. for the design and assembly of the coating heads. The authors would also like to thank [PERSON] and [PERSON], CSER, for their help in the commissioning of the SPARC inline deposition system. [PERSON] and [PERSON] are also acknowledged for their contributions to the PLC programming on the system.  
**Conflicts of Interest:** The authors declare no conflict of interest.