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This work describes the electrodeposition of ZnO layers on p-type copper indium gallium diselenide [Cu(InGa)Se2] substrates via nitrate ions reduction in the presence of thiourea. The substrate stability domain has been determined by means of cyclic voltammetry in acidic medium. The optimal deposition range has been studied in zinc nitrate electrolyte containing concentrations of thiourea between 0 and 1.0 M. Zinc oxide films have been photoelectrodeposited in a potential range between − 0.95 and − 1.1 V/MSE depending on thiourea concentration. The morphology and composition analyses by scanning electron microscopy, X-ray diffraction spectroscopy, and energy dispersive X-ray spectroscopy have highlighted that the deposited films are composed of well-crystallized ZnO presenting wurtzite-type structure with no significant sulfur incorporation.

This paper reports the first implementation in our laboratory of a chemical–mechanical polishing (CMP) process for CdZnTe (CZT) substrates prepared for growth of HgCdTe layers by liquid phase epitaxy and molecular beam epitaxy. The process enables significant reduction of the thickness of the damaged zone induced by the mechanical polishing that must be etched away before epitaxy. Resulting improvements in surface morphology, in terms of waviness and density of point defects, are reported. The chemical state of surfaces polished by CMP was characterized by x-ray photoelectron spectroscopy. The chemical state was highly homogeneous; comparison with a reference surface is reported. End use assessment of this surface processing was compared with that of reference substrates by preparation of focal-plane arrays in the medium-wavelength infrared spectral range, by using epitaxial layers grown on substrates polished by different methods. The electro-optical performance of the detectors, in terms of photovoltaic noise operability, are reported. The results reveal that the state of this CMP surface is at the level of the best commercial substrates.

Zn(S,O,OH) Chemical Bath Deposited (CBD) remains one of the most studied Cd-free buffer layer for replacing the CBD-CdS buffer layer in a Cu(In,Ga)Se2-based (CIGSe) solar cells and has already demonstrated its potential to lead to high-efficiencies. However, in order to further increase the deposition rate of the Zn(S,O,OH) layer during the CBD, the inclusion of additives can be a reasonable strategy, as long as the efficiencies of solar cells are maintained. The aim of this work is to understand the effect of the introduction of additives such as hydrogen peroxide (H2O2), H2O2+ethanolamine (C2H7NO) and H2O2+tri-sodium citrate (Na3C6H5O7) during CBD on the deposition mechanism, the growth rate and the quality of the buffer layer. It has been shown that the combined use of H2O2 and citrate in the bath formulation allows the deposition of Zn(S,O,OH) via a mix of “ion-by-ion” and “cluster-by-cluster” mechanisms that have good properties as buffer layers leading to high efficiency solar cells.

The ability to pattern HgCdTe surfaces using a wet etching solution is an important challenge for processing of third-generation infrared detectors. The reduction of pixel size, the increase of pixel density, and two-color array technology require perfectly mastered etching to remove very thin layers and to control the state of the surface. To perform this process, a new quantitative chemical approach was developed to carry out very accurate wet etching in aqueous HBr/Br2 solutions. This approach was established to identify the key parameters that govern the etching process and to understand the etching mechanism.

In this paper, we investigate the properties of porous structures anodically grown onto n-InP (100) in HCl. In situ electrochemical characterizations show the pore morphology strongly influences the properties of the InP surfaces. Both dc- and ac-electrochemical measurements reveal an enhancement of the capacitive current and a modification of the electronic distribution at the interface. Photocurrent spectra performed during the pore growth are also strongly modified. For low anodic charges, an increase of the photocurrent with a redshift of the absorption edge is measured. These evolutions can be respectively ascribed (i) to a reflection decrease due to a surface roughening and (ii) to the creation of surface states within the band gap. For higher anodic charges, the photocurrent drops with a narrowing of the spectrum. Using a model based on the “dead” layer, the porous layer is considered as an absorbent film that progressively attenuates the photocurrent of the bulk semiconductor.

We characterize the surface of molecular-beam epitaxy (MBE)-grown CdTe(211)B/Ge(211) by atomic-force microscopy (AFM), optical interference microscopy, and generalized ellipsometry (GE). We find that, for substrate temperatures above 300°C, the surface is rough and hazy; the AFM root-mean-square roughness is of the order of 150 A. It appears from GE that the optical response is anisotropic, the principal axes of anisotropy being along the \( [\overline{1} 11] \) and \( [0\overline{1} 1] \) directions. For a substrate temperature of approximately 300°C, the surface is smooth and mirror-like and the AFM roughness is as low as 45 A. The sample is still anisotropic, even though the magnitude of the cross-polarized reflection coefficients are very small in this case. It appears that the anisotropy originates from the surface roughness, not the bulk.

We study the surface chemistry of Cd0.96Zn0.04Te(211)B by X-ray photoelectron spectroscopy and ellipsometry. We obtain first the dielectric functions of amorphous Te and Cd on Cd0.96Zn0.04Te(211)B by in␣situ ellipsometry after growing thin films of each material by molecular beam epitaxy. We then study their oxidation in air and show that Cd oxidizes primarily as a hydroxide whereas Te is present as TeO2. In neither case is the oxidation of the films complete, as a substantial amount of either metallic Te or Cd remains even after several days of oxidation. We subsequently exploit an electroless chemical etchant based on Ce4+ to produce Te-rich Cd0.96Zn0.04Te(211)B surfaces which oxidize very little in air. Another etchant containing KCN reduces the amount of α-Te substantially. Finally, we construct a tentative optical model for the Cd0.96Zn0.04Te(211)B surface that yields the abundance of amorphous Te on the surface.

This paper deals with the behaviour of two Keggin-type heteropolyanions: SiMo12O4−40 and SiW12O4−40 dissolved in aqueous acidic solution, towards semiconductors, at rest potential. Two III-V semiconductors are studied, GaAs and InP. At the material/solution interface, GaAs undergoes an oxidation/dissolution process while the heteropolyanions are reduced. These reactions lead to the growth of a film on the GaAs surface, its composition was determined by X-ray photoelectron spectroscopy. In the dark, at the InP/solution interface no reaction occurs whatever the heteropolyanion used. However, in the presence of SiMo12O4−40, when an n-type InP semiconductor is illuminated (hυ>1.35 eV) the heteropolyanions are reduced and the photodissolution of the material is achieved, no surface film is present on the etched surface. The difference of behaviour between GaAs and InP is primarily due to the difference of the positions of the semiconductor energy-band edges with respect to the first redox potential of the heteropolyanions.

In order to qualify the reactivity of various aluminium and silicon oxide substrates for elastomer adhesion applications, X-ray photoelectron spectroscopy (XPS) and rest-electrochemical potential measurements have been performed on those surfaces. The interpretation of XPS binding energy shift measurements in terms of Fermi level variation from one surface to another, as proposed by Mullins and Averbach in 1988, is discussed in view of results on an aluminosilicate compound surface. The correlation with electrochemical restpotential measurements on an anodized aluminium surface and a silane coupling agent is described and discussed. The possibility of surface reactivity assessment through correlated XPS and electrochemical measurements for metal oxides is demonstrated.

Hydrogen (deuterium used as tracer) diffusion experiments were performed on undoped and boron doped diamond films ([B] = 1019and 1020 cm−3) grown by plasma CVD or hot-filament assisted CVD. The samples were exposed either to a radiofrequency plasma or a microwave plasma at different temperatures between 400°C and 900°C. The deuterium profiles were analysed by secondary ion mass spectrometry (SIMS). The deuterium diffusion was explained mainly in term of trapping on intergranular defects. The passivation of boron acceptors, by B-D complex formation in the deuterium diffused superficial layers of the diamond films, was followed by electrochemical and mercury probe capacitance measurements. The results suggest a strong decrease of the free carrier density, which is in accordance with passivation of free carriers by deuterium trapping on dopant.