Supercritical Fluid Electrodeposition of Elemental Germanium onto Titanium Nitride Substrates. Issue 14 (16th October 2015)

• Record Type: Journal Article
• Authors: Cummings, Charlie Y.; Bartlett, Philip N.; Pugh, David; Reid, Gillian; Levason, William; Hasan, Mahboba M.; Hector, Andrew L.; Spencer, Joe; Smith, David C.
• Is Part Of: Journal of the Electrochemical Society. Volume 162:Issue 14(2015)
• Page Start: D619
• Page End: D624
• Publication Date: 2015-10-16
• Subjects: Difluoromethane -- Electrodeposition -- Germanium -- Supercritical fluid -- Titanium nitride; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0771514jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : We report the electrodeposition of germanium from supercritical difluoromethane (sc-CH2 F2 ) at 19 MPa and 358 K using [N n Bu4 ][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.