Single-crystal ingots of CdTe and Cd0,96Zn0.04Te 60–100 mm in diameter were grown by directional solidification using the self-seeding technique. The microstructure of the crystals was checked by optical microscopy, electron microscopy (TEM, SEM and EBIC), cathodoluminescence, and X-ray diffraction. It was found that crystal perfection depends to a large measure on the temperature schedule during Lpostgrowth crystal cooling: special caution should be exercised in the temperature interval including the polymorphous transformation. A direct relationship between optical and electronic properties on the one hand and crystal microstructure on the other hand was established.

The nonuniform temperature distribution in a crystal surface during ultrasonic loading has been detected. This effect was associated with a sonic-stimulated temperature rise around dislocations and heating of the nonperfect regions of the samples investigated. The dislocation moved in an ultrasonic field was considered as a linear thermal source. We calculated the temperature distribution around dislocations and determined conditions of the discrete and continuous distribution of thermal sources for Hg$_{1-x}$CdxTe alloys. We also discuss the possibility of using the investigated effect as the basis of a non-destructive technique for extended defect mapping and imaging in crystals.

Different GaAs-matched epitaxial structures based on InGaP and InGaAlP layers were prepared by LP MOVPE. The suitable p- and n-type sequence of these layers will be used as active elements in high efficiency solar cells. The layers were grown on (001) GaAs substrates oriented 2° off towards (110) using trimethylgallium (TMG), trimethylaluminium (TMA), trimethylindium (TMI), arsine (AsH3) and phosphine (PH3) as main reagents and dimethylzinc (DMZ) and silane (SiH4) as p- and n-type doping reagents, respectively. The layers have been analyzed as regards their compositional homogeneity, interface abruptness and doping concentration by different techniques such as SIMS, TEM and AFM. The combined analysis of SIMS and TEM has been of great usefulness in order to define the abruptness of composition change. Moreover an analysis of autodoping effects is reported as regards the arsenic diffusion in InGaP matrix and the analysis of different samples is reported.

The errors of surface profile measurements using grid-illumination Makyoh topography is analysed using computer simulations. It is shown that two regions of imaging exists: at smooth surfaces and small screen-to-sample distances, the error is determined by the pixel reading error, while at less smooth surfaces and larger screen-to-sample distances, the errors of summation approximation dominates. The pixel reading error component can be decreased by increasing the screen-to-sample distance. It is demonstrated that the described evaluation algorithm gives maximum relative errors of roughly 1.5%.

We have developed a method for growing high quality multicrystalline silicon (mc-Si) ingots for high efficiency solar cells. Grain size of the mc-Si wafers was controlled by the multi-stage solidification method. Impurity concentrations in the mc-Si ingots were also reduced by several ways. The efficiency of mc-Si solar cells produced from such mc-Si wafers has reached 18.3% with a cell area of 25 cm2. In this paper we have investigated this high quality mc-Si by means of electron-beam induced current (EBIC), transmission electron microscopy combined with energy-dispersive X-ray analysis (TEM-EDX), and secondary-ion mass-spectroscopy (SIMS). EBIC results revealed that grain boundaries in MUST mc-Si were electrically inactive at room temperature. No metal impurities were detected at these grain boundaries.

Optical second harmonic (SH) imaging using femtosecond laser pulses (782 nm, 80fs) is applied to investigate the structural quality of SiC and ZnO thin films grown by chemical vapour deposition (CVD) on Si(100) substrates. We find a spatially uniform SH response from the SiC sample as well as a regular 4-fold symmetry (3C-SiC-(001)) in the rotational SH anisotropy. The ZnO film is poly-crystalline as indicated by a strongly position dependent SH response and the missing regularity in the rotational SH anisotropy. The estimated grain size is ~ 30−50 µm. Furthermore our time dependent SHG measurements on native Si/SiO2 for laser peak intensities up to 100 GW/cm2 indicate that hole injection and trapping into the ultrathin SiO2 layer contributes to the SH signal above $\geq 45$ GW/cm2. The SHG images of defects irreversibly induced in Si/SiO2 under laser irradiation are reproduced by scanning electron microscopy (SEM).

A specific experimental Laser Scattering Tomography (LST) acquisition procedure is presented. It is adapted to the characterization of materials containing scattering defects ranging from 1 to 102/mm3. The technique makes it possible to obtain good resolution within a volume chosen to contain a statistically significant defect density. This method is used to show that the gas levitation technique makes it possible to significantly decrease scattering defects in glasses. In parallel, individual study of defects in such glasses is also presented.

The long-term diffusion processes of defects in HgxCd$_{1-x}$Te mixed crystals were investigated. Measurements of reflectivity and surface characterisation by means of scanning electron microscopy (SEM) were performed for samples with x = 0.4 and x = 0.62. The experiments were repeated after wet chemical etching. Optical results were compared with the reflectivity spectra obtained 20 years ago using the same samples of investigated material. We discuss the observed large changes in the optical spectra on the basis of comparative analysis and SEM results.

A technology of anisotropic etching of GaAs (100) samples with two different types of geometric disorder (dendrite, quasi-grating) has been elaborated. The geometric statistical parameters of micro(nano)relief were investigated using bearing analysis. The measurements of the radii of curvature have shown that the samples were rather deformed, with nonuniform strain lateral distribution over the wafer areas. The radii of curvature were different for different samples, depending on surface treatment. The X-ray diffraction data indicate that the subsurface region of anisotropically etched GaAs crystal and epitaxial films grown on such substrates are not worse than those of a crystal with smooth chemically polished surface. Geometric disorder of such surfaces leads to enhancement of the diffuse contributions on the rocking curve tails.

The use of white light interference microscopy for the non-destructive 3D measurement of an interface buried under a transparent layer has been investigated. Test samples consisting of step structures (< 2 µm) etched in silicon and then covered by a thick (> 1 µm) layer of resin have been studied. The 3D morphology of the buried step was successfully measured through the transparent layer. Comparison of the step heights measured before and after the deposition of the resin layer shows a reduction in the estimated measurement precision from 4% in air to 9% through the transparent layer. The additional errors arise from optical aberrations due to the roughness and the geometry of the air/resin surface, the thickness of the layer and possibly from inhomogeneities in the refractive index of the layer that contribute to a degradation of the wavefront reflected from the interface.

Defects in the Si layered structures, Si:H(D), prepared by implantation with H2+/D+, and their changes resulting from the treatment under enhanced pressure (HP), were investigated by X-ray diffraction and transmission electron microscopy (XTEM). Such treatment affects out-diffusion of hydrogen (deuterium) as well as the shape and concentration of the H(D)-filled cavities. The relation between X-ray and XTEM results is discussed.

Since the majority of bulk crystal growth methods involves melt freezing, the knowledge of the molten state properties is one of the most important parameter coming into the improvement of the growing crystal and method. It is well known that melting of covalent semiconductor destroys covalent bonds and induces metallic type liquid. The phenomenological model of viscosity developed by Kim and Chair has demonstrated very good agreement for normal liquid, helium or monoatomic metals. In this paper, we propose to use it in the case of semiconductor melts.

GaSb and AlSb are very interesting semiconductors widely used in multiple applications such as optoelectronics or thermophotovoltaic cells. AlSb has higher band gap than GaSb but very similar lattice parameter, which allows the fabrication of lattice-matched films with different energy band gap over GaSb substrates. Moreover the ternary alloys, in the system AlxGa1−xSb, are very interesting for semiconductor device engineering where the capacity of creating lattice-matched heterostructures with different band gap is very important. In this work, we present a study on the formation of AlxGa1−xSb films on GaSb substrates by Al diffusion. Al thin films were evaporated over GaSb substrates and then annealed with different time and temperature conditions. RBS measurements has been performed to analyze the diffusion profile and to calculate the thickness of the AlxGa1−xSb films. The dependence of the characteristics of the films with annealing time and temperature is analyzed. EDAX and XRD analysis have been performed to calculate the specific composition of the alloy depending on the film growth parameters

The ternary alloys PbxCd1−xTe were prepared by the vertical Bridgman method and studied from a morphological viewpoint. The evolution of the different defects with the Pb concentration was described. For x = 0.20, strong segregation was found. A supercrystal structure, formed by alternated layers of CdTe and PbTe was encountered in the PbTe rich phase. We propose some hypothesis about the mechanism for their formation. An interpretation of the optical behavior in the 0.2–0.6 eV infrared region will be also presented.

Transmission electron microscopy, high resolution X-ray diffraction, cathodoluminescence were performed on strain balanced InGaAs based multi-quantum wells (MQWs) to be used as active layers in thermophotovoltaic devices operating at around 2 µm. The epitaxial growth front in the MQWs is flat up to a certain thickness where a change in the growth mode generates MQW waviness propagating vertically through the structure with increasing amplitude. The local stress concentration in the MQW regions exhibiting significant local rippling results in the formation of clusters of extended defects whose properties vary according to the strain and the growth temperature conditions of the structures. Experimentally it has been found that the wavy growth onset occurs once a threshold value of the elastic energy density is achieved. The well/barrier thickness ratio were changed in order to minimize this threshold energy and thus to retain good material quality even at the longer wavelength. Forty repetitions defect free MQWs, emitting at 1.96 µm at room temperature were successfully grown in this way.

In this work, we address the problem of identifying the minimum temperature required to diffuse copper deposited at the silicon surface into the bulk, and to identify a suitable method to detect the initial stages of copper electrical activity at wafer surface. Thermal treatments at temperatures ≥250 °C were studied. It is shown that after an annealing at temperatures ≥250 °C a significant copper fraction diffuses in silicon, but it is not electrically active for carrier recombination. In addition, after these treatments copper at the silicon surface cannot be completely removed by cleaning. A moderate electrical activity is associated to copper at the oxide-silicon interface in the native oxide A change in the chemical bonds of copper is detected by XPS after annealing at 700 °C. After a further annealing at 900 °C, copper is electrically active for recombination both at the surface and in the bulk.

Synchrotron X-ray topographs were taken for bonded silicon-on-insulator wafers. Under the grazing incident condition, the topographs of the top Si layer and the substrate are similar, which represent the variation in incident angle due to surface undulation. Furthermore, a circular concentric pattern was observed in the topographs of the top Si layer both at the grazing and higher incident angles. This shows that the concentric pattern is not due to surface undulation, but due to lattice distortion.

Crystal distortions modify the propagation of X-rays in single crystal materials, and X-ray topography can be used to record these modifications on a film thus providing images of the distributions and nature of defects, dislocations, strains, precipitates, etc. in semiconductors. Small variations of contrast, which often need to be analysed can be rendered invisible. Furthermore, artefacts in the films must be removed. This study examines the use of advanced image analysis techniques applied to a selection of X-ray topographs in section transmission mode: (i) the automated counting of oxygen-related precipitates and (ii) the enhancement of Pendellösung fringes. The technique also succeeds in removing unwanted features in the original x-ray topographs such as vertical streaking due to collimating slit phase contrast and strain features near the surface due to the presence of integrated circuit process strains.

In order to investigate oxidation-induced stacking faults (OSF), Cu-decorated Si wafers have been examined by dark-field optical microscope (OM), transmission X-ray topography (XRT), and scanning photoluminescence (sPL). It is found from OM observation that there are bright pits with several 10 µm sizes, forming a single ring, although there are many fine pits. On the other hand, a few subsidiary rings, in addition to the main OM ring, are observed by XRT and sPL measurements, although they do not directly correlate each other. It is found from microscopic PL measurement that there are dark spots, corresponding to the bright OM pits in the main OSF ring. By comparing the OM and sPL results, it is clearly found that the dark PL spots are corresponding not to fine OM pits but large OM pits with several 10 µm sizes, which seem to be due to copper oxides or precipitates on the surface. It may be emphasized that the sPL technique presented here may be used instead of OM to observe the OSF ring in Cu-decorated Si wafers, and also instead of XRT to observe the OSF ring in standard Si wafers annealed without copper decoration, because PL is more sensitive than OM observation and its intensity is related to the lifetime and concentration of carriers.

We present microscopically-resolved photocurrent spectroscopy as a new powerful analytical tool for the simultaneous detection of packaging-induced strain and defects in GaAs-based high-power laser diode arrays (cm-bars). Using the Fourier-transform (FT) technique we measure photocurrent (PC) spectra with a high spatial resolution of better than 50 μm at the active layer of the device. By analyzing this data, spatially resolved distributions of strain as well as of defects are obtained. So far, PC measurements at cm-bars have only provided an overview of the distribution of strain and defects in the device on an emitter-by-emitter scale. The high spatial resolution now allows examination of the distribution of strain and defects even within one single emitter. This is essential for obtaining insights into device failure mechanisms and also makes a substantial contribution for improving device performance and reliability.