Valentin M. Kozlov

Intermetallic compound formed by electrodeposition of indium on antimony

Abstract Indium galvanostatic electrodeposition from aqueous solutions on antimony electrodes has been investigated together with time evolution of the deposit composition. The morphology, composition and structure of the deposit surface and cross-section have been analysed by SEM-EDS and X-ray diffraction both before and after annealing at 70, 110 and 135°C for increasing times. The results showed the formation of InSb, owing to indium diffusion into the bulk of the cathode and to the reaction with antimony. The indium diffusion coefficient in InSb between 25 and 135°C (from 0.1×10−19 to 2.6×10−19m2s−1) has been estimated from X-ray data and the values of the activation energy (30 kJ mol−1) and preexponential factor (1.8×10−15 m2 s−1) have been determined.

Formation of structural defects during non-coherent nucleation : An atomistic analysis

The mechanism of formation of the main structural defects during metal deposition has been investigated on the basis of atomistic considerations, aiming to relate quantitatively the crystallization overvoltage the dislocation density and the average grain size of the deposits. The theoretical behaviour was verified by the experimental findings on Zn electrodeposition.

Formation of structural defects during metal electrocrystallization

The mechanism of formation of the main structural defects during metal electrodeposition has been investigated by performing a thermodynamic analysis of crystal growth through non-coherent 3D nucleation when the substrate does not influence the process any more.

Influence of the nature of metals on the formation of the deposit's polycrystalline structure during electrocrystallization

Abstract The influence of the nature of metals on the formation of the deposits polycrystalline structure during electrochemical crystal growth has been investigated. Cd, Cu and Ni were selected for the theoretical simulation, they being typically representative of each of the three classes into which metals are traditionally divided according to their increasingly slower kinetics. The theoretical results confirm previous classification and substantially agree with the experimental ones on Cd, Cu and Ni electrodeposition.

Influence of the structure of the electrodeposited antimony substrate on indium diffusion

Abstract The influence of the morphology and structure of antimony substrates on the diffusion and reaction process of an electrodeposited indium overlayer was investigated. The formation of the InSb intermetallic compound was studied by SEM-EDS and X-ray diffraction, at temperatures of 40, 70, 110 and 140°C. The antimony substrates, either crystalline or amorphous, were prepared by electrodeposition, the former being obtained in two different conditions, i.e. from a bath either not containing or containing the surface-active agent, Trylon B. The lowest indium diffusion coefficient was observed for the crystalline substrate prepared in the presence of the organic compound and the highest for the amorphous substrate, in spite of the higher surface roughness of the crystalline material. The values ranged from 0.35×10 −19 to 17.1×10 −19 m 2 s −1 , at 70°C. This behaviour was ascribed to the lower activation energy for In diffusion in the amorphous phase (53 instead of 65 kJ mol −1 ) which has a more open structure and lower density than the crystalline structure, due to the larger interatomic distances.

Influence of foreign particle adsorption on the formation of structural defects during noncoherent nucleation: an atomistic analysis

Abstract The influence of surface adsorption of foreign particles on the formation of the main structural defects during metal deposition was investigated, aiming to quantitatively relate the surface coverage, the dislocation density and the average grain size of the deposits. The theoretical results were verified by the experimental findings on NiP electrodeposits.

Influence of temperature and of structure of antimony substrate on gallium diffusion into the GaSb semiconductor compound

Abstract The diffusion coefficient of Ga electrodeposits on Sb electrodeposited thin films, either amorphous or crystalline, was investigated to determine the influence of the morphology and structure of the antimony substrates on the diffusion and reaction process. The Ga/Sb bilayer was studied by SEM–EDS and X-ray diffraction before and after heating at temperatures of 50, 75 and 100°C. The formation of the GaSb semiconductor compound was particularly considered and the activation energy and frequency factor of the process was determined. At these temperatures, Ga was at least partially molten and the diffusion coefficient showed that the geometrical factor was prevailing over the structural one. For example, at 75°C, the values of the diffusion coefficient were 1.5×10 −17 and 6.3×10 −17 m 2 s −1 for the amorphous and crystalline antimony, respectively. On the contrary, at 20°C, a temperature at which Ga is in the solid state, the structural factor prevailed over the geometrical one and values were obtained lower by around three orders of magnitude. The prevailing influence at 20°C was identical to that previously observed for In diffusion into amorphous and crystalline Sb with InSb formation. The experimental results, both at low and high temperatures, are discussed also taking the behaviour of the In–Sb system into account.