Copper, tin and zinc have been co-electrodeposited on Mo-coated glass substrates from an aqueous acid sulfate solution at room temperature with the aim of preparing kesterite absorber layers for solar devices. The solution contains copper, tin and zinc sulfate, potassium sulfate and sodium citrate at pH = 4.75. The effect of two complexing agents (sodium citrate and tartaric acid) is characterized by solution chemistry analysis, by voltammetry using a rotating disk electrode and an electrochemical quartz crystal microbalance. A deposition process is developed to co-deposit the three metals with the appropriate composition (copper poor and zinc rich). Deposition kinetics has been investigated. The composition can be tuned by mass transport control and by deposition potential. Composition, morphology and structure are characterized by Inductively Coupled Plasma analysis, Energy Dispersive X-ray Spectrometry coupled to Field Emission Scanning Electron Microscopy and X-ray Diffraction. The co-deposited layers are porous due to dendritic growth. After annealing at 530°C during 15 min in a selenium atmosphere, a 5.8% solar cell efficiency has been obtained.

No abstract

Iron epitaxial electrodeposition on Au(111) substrates is investigated using in situ scanning tunneling microscopy (STM) and ex situ X-ray diffraction (XRD). STM observations show that Fe grows quasi layer-by-layer at sufficiently negative potentials. XRD results indicate that Fe layers thicker than 3 ML are bcc and present the epitaxial relationship Fe(110) [1−10]||Au(111) [11−2]. They also show that the Fe lattice is uniaxially in-plane strained along Fe[1−10] and that the strain is progressively relieved with increasing layer thickness. The growth of Fe on a Ni layer deposited on Au(111) leads to strain free Fe layers with the same epitaxial relationship. The specific shape of Fe of monatomic islands suggests that the first Fe monolayer deposited on Au(111) presents a centered rectangular lattice similar to that of bcc Fe(110) but is stretched along Fe[1−10] by more than 8%.