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SiC-on-Insulator (SiCOI) structures fabricated using the Smart Cut™ technique can be of great interest in order to probe the properties of a silicon carbide (SiC) transferred layer, by electrically insulating it from the receiver substrate. In this study, we report the fabrication of such a SiCOI structure using a SiC receiver, as well as its electrical and TEM characterization after high temperature annealing. We highlight a decrease of the transferred layer electrical resistivity with increasing annealing temperature, due to doping reactivation and electron mobility enhancement. After low temperature annealing (1200°C to 1400°C), deep acceptor levels, possibly located in a damaged region near the substrate’s surface, might be responsible of a non negligible electrical compensation. Beyond 1400°C however, the transferred SiC crystal is healed and electron transport is only subjected to shallow nitrogen ionization.

Ge epitaxy on nanometer-size Ge pillars was studied in a 300 mm industrial Reduced Pressure-Chemical Vapour Deposition tool. A patterning scheme based on diblock copolymer lithography was used to fabricate honeycombed nanometer-sized Si templates for the hetero-epitaxy of Ge nano-pillars. It was highly selective and uniform at 600°C. Thick Ge layers were then grown with a low temperature/high temperature approach on Ge nano-pillars and characterized by Atomic Force Microscopy, X-Ray Diffraction and cross-sectional Transmission Electron Microscopy. A degraded surface morphology, with otherwise similar structural properties was obtained for 2D Ge layers grown on Ge nano-pillars compared to growth on bulk Si. Defects such as stacking faults and twins also formed during the coalescence process.

Low contact resistances are required to continue the miniaturization of CMOS devices and improve the performances of group IV semiconductors’ photodiodes and light emitting devices. In this study, we tried to enhance the electrical activation in in-situ boron-doped germanium by nanosecond laser annealing (NLA), an ultrafast, non-equilibrium process. Similar annealing regimes than that evidenced on SiGe thin layers were seen. Surface structures with shapes and orientations comparable to that after SiGe NLA were found in the surface melt regime. When the entire Ge:B layer was melted, we obtained a flat surface with a root mean square roughness of 1.51 nm. Laser annealing resulted in a redistribution of B, with the formation of electrically inactive clusters that did not contribute to strain. Accordingly, the sheet resistance increased by 70%, from 39.82 Ω/□ up to 68.62 Ω/□, when the layer was melted. This corresponded to an electrically active carrier loss of around 50%, from 8.1x1020cm-3down to 3.8x1020cm-3. Even multiple pulses with various energy densities at the same position were not able to improve electrical activation. However, there was some slight improvements of the sheet resistance in the sub melt regime, which needs to be confirmed in future experiments.

The structure of the [011] σ = 9 and σ = 11 symmetrical tilt grain boundaries in germanium, very close to the exact coincidence orientation, has been studied using the α-fringe and electron diffraction techniques. Diffraction patterns from the grain boundary at various inclinations were recorded, those at normal incidence examined in detail, and fine matrix and double-diffracted spots identified. The boundary zones are dilated, and from the results of both techniques we can conclude that there is no rigid body translation parallel to the grain boundary. The σ = 9 periodicity is that of the coincidence site lattice, while that of the σ = 11 bicrystal is double. In both cases there is a glide-reflection plane parallel to the grain boundary which leads to the existence of favourable, symmetrically alternated atomic arrangements. Five-ring and seven-ring units and "boat-shaped" six-ring units are combined in geometrical models without dangling bonds.

We have checked whether or not the Low Temperature / High Temperature approach used for pure Ge growth on Si yielded high quality Si0.5Ge0.5Strain-Relaxed Buffers (SRBs) that could serve afterwards as templates for thick Ge layers. We had, as soon as the Si0.48Ge0.52layers grown at 550°C plastically relaxed, a surface roughening which was not recovered by the 850°C growth of Si0.5Ge0.5(rms roughness: 5 nm). Thickening it with Ge at 750°C and using a Thermal Cycling yielded a slight surface roughness decrease, however (down to 4 nm). The HT Si0.5Ge0.5and pure Ge layers were slightly tensile strained. This was due to thermal expansion coefficient differences between Si and SiGe (Ge) coming into play during the cooling-down to room temperature. We had otherwise used the Ayers’ theory in order to transform the full widths at half maximum of SiGe and Ge X-Ray Diffraction omega scans into Threading Dislocations Densities. We would then have, for 60° misfit dislocations in our stacks, the following values: 3.5x108cm-2in annealed 1.7 µm thick Si0.5Ge0.5SRBs and 1.6x108cm-2in the 1.3 µm thick Ge layers on top. Those values were definitely higher than those in 1.4 µm thick, cyclically annealed pure Ge layers grown directly on Si and in the top part of ~ 6 µm thick Si0.5Ge0.5linearly graded virtual substrates.

Deals with (i) the growth and thermal stability of large number or periods SiGe/Si superlattices on bulk Si and (ii) the impact of B and P doping and of C alloying of SiGe on the growth kinetics of SiGe/Si superlattices.

In non-volatile memories, high-k materials such as Al2O3, HfO2, and hafnium aluminates are good candidates as interpoly layers. In order to decrease the parasitic trapping of the interpoly stack, the effect of post deposition nitridation (PDN) on different high-κ films was investigated. Several characterizations were performed on those films such as Angle Resolved X-ray Photo-electron Spectroscopy (AR-XPS), Auger Electron Spectroscopy (AES), Attenuated Total Reflection - Fourier Transform Infrared spectroscopy (ATR-FTIR) and Vacuum UltraViolet Spectroscopy Ellipsometry (VUV-SE). A correlation between the nitrogen incorporation and the crystallization was demonstrated. Al-rich films remain amorphous after PDN, with an incorporation of nitrogen in the film volume. Meanwhile, Hf-rich films crystallized after PDN, with nitrogen incorporated only at the high-κ / Si substrate interface. Also nitrogen increases the crystallization temperature onset, which leads to a reduction of charge trapping after high temperature spike anneals. Nitrided amorphous hafnium aluminate films are good candidates as interpoly layer.