Supercritical fluid electrodeposition of elemental germanium onto titanium nitride substrates

Charlie Y. Cummings, Philip N. Bartlett, David Pugh, Gillian Reid, William Levason, Mahboba M. Hasan, Andrew L. Hector, Joe Spencer, David C. Smith

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

We report the electrodeposition of germanium from supercritical difluoromethane (sc-CH2F2) at 19 MPa and 358 K using [NnBu4][GeCl3]. Voltammetry shows a classic nucleation loop on the first anodic scan with a high nucleation overpotential for germanium on TiN. In all cases the deposition appears to be kinetically limited by a coupled, potential independent, chemical step. Films of germanium were deposited at a range of potentials. At high overpotentials the films were dendritic and poorly adherent. At lower overpotentials, below -2 V vs. Ag|LaF3, the films are smoother and more homogeneous. Analysis of the films by energy dispersive X-ray (EDX) spectroscopy shows the presence of germanium with some chloride impurity. Raman spectroscopy confirms the deposition of amorphous germanium. Plating by pulsing to -1.9 V vs. Ag|LaF3 for 100 ms and then growth at -1.5 V vs. Ag|LaF3, was found to produce the best films. On annealing at 700°C under an Ar atmosphere for 1 hour the as-deposited amorphous germanium film is converted into crystalline germanium, as determined by X-ray diffraction (XRD) and Raman spectroscopy.

Original languageEnglish
Pages (from-to)D619-D624
JournalJournal of the Electrochemical Society
Volume162
Issue number14
DOIs
StatePublished - 2015
Externally publishedYes

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