Ferroelectric epitaxial Pb(Zr,Ti)O3 (PZT) layers were grown by pulsed laser deposition on SrTiO3/GaAs templates fabricated by molecular beam epitaxy. The templates present an excellent structural quality and the SrTiO3/GaAs is abrupt at the atomic scale thanks to surface Ti pre-treatment. The PZT layers contain a- and c- domains, as shown by X-Ray diffraction analyses. Piezoforce microscopy experiments and macroscopic electrical characterizations indicate that PZT is ferroelectric. A relative dielectric permittivity of 164 is extracted from these measurements.

The optical properties of an InAsP/InP quantum well grown on a SrTiO3(001) substrate are analyzed. At 13K, the photoluminescence (PL) yield of the well is comparable to that of a reference well grown on an InP substrate. Increasing the temperature leads to the activation of non-radiative mechanisms for the sample grown on SrTiO3. The main non-radiative channel is related to the thermal excitation of the holes to the first heavy hole excited state, followed by the non-radiative recombination of the carriers on twins and/or domain boundaries, in the immediate vicinity of the well.

This work reports on the epitaxial growth of crystalline high-k Gd2O3 on Si (111) by Molecular Beam Epitaxy (MBE) for CMOS gate application. Epitaxial Gd2O3 films of different thicknesses have been deposited on Si (111) between 650°C~750°C. Electrical characterizations reveal that the sample grown at the optimal temperature (700°C) presents an equivalent oxide thickness (EOT) of 0.73nm with a leakage current density of 3.6×10-2 A/cm2 at |Vg-VFB|=1V. Different Post deposition Annealing (PDA) treatments have been performed for the samples grown under optimal condition. The Gd2O3 films exhibit good stability and the PDA process can effectively reduce the defect density in the oxide layer, which results in higher performances of the Gd2O3/Si (111) capacitor.

Indium phosphide (InP) nanowires (NWs) were grown by molecular beam epitaxy on various substrates including SrTiO3 (001), Si (001) and InP (111) at a growth temperature of 380°C. We used the Vapor Liquid Solid assisted method with Au as a metal catalyst. The composition of the catalyst particles and the crystalline structure of the nanowires were compared using reflection high energy electron diffraction, scanning electron microscopy and high resolution transmission electron microscope. It is found that InP nanowires grown onto InP and SrTiO3 substrates are structurally defects free with a wurtzite structure. On Si (001) substrates, the presence of stacking faults and cubic phase insertion along the growth direction is observed. The effect of the substrate on the composition of catalyst droplets and consequently on the crystalline quality of the nanowires is discussed for the conditions of nucleation and defect formation.

High-resolution synchrotron radiation X-ray photoelectron spectroscopy (HRXPS) is used to study the chemical bonding at the Al2O3/Si(001) and Al2O3/Si(111) interfaces. In both cases, the Si2p spectra recorded at 180 eV photon energy provides evidence a thin interfacial layer rich in Si-O bonding. On the other hand, conventional AlKα X-ray source angular measurements clearly indicate that there are two in-plane orientations for Al2O3/Si(111) : [11-2]Al2O3(111)//[11-2]Si(111) and [-1-12] Al2O3(111)//[11-2]Si(111) but four in-plane orientations for Al2O3/Si(001) : [11-2] Al2O3(111)//[100]Si(001), [11-2]Al2O3(111)//[010]Si(001), [11-2]Al2O3(111)//[-100]Si(001), and [11-2]Al2O3(111)//[0-10]Si(001).

Amorphous LaAlO3 high-k oxide was grown in a molecular beam epitaxy reactor on p-Si(001) using a thin γ-Al2O3 epitaxied buffer layer. Interfaces were free of SiO2 or silicates and remained abrupt despite the high temperature used for annealing, as X-ray photoelectron spectroscopy showed. Electrical measurements performed on as-deposited samples revealed a dielectric constant value close to that of the bulk, small equivalent oxide thickness and low density of interface states. But some negative charges were present, leading to a flat band voltage shift. Post deposition annealing with forming gas can correct this effect.

One of the major challenges during recent years was to achieve the compatibility of III-V semiconductor epitaxy on silicon substrates to combine opto-electronics with high speed circuit technology. However, the growth of high quality epitaxial GaAs on Si is not straightforward due to the intrinsic differences in lattice parameters and thermal expansion coefficients of the two materials. Moreover, antiphase boundaries (APBs) appear that are disadvantageous for the fabrication of light emitting devices. Recently the successful fabrication of high quality germanium layers on exact (001) Si by chemical vapor deposition (CVD) was reported. Due to the germanium seed layer the lattice parameter is matched to the one of GaAs providing for excellent conditions for the subsequent GaAs growth. We have studied the material morphology of GaAs grown on Ge/Si PS using atomic layer epitaxy (ALE) at the interface between Ge and GaAs. We present results on the reduction of APBs and dislocation density on (001) Ge/Si PS when ALE is applied. The ALE allows the reduction of the residual dislocation density in the GaAs layers to 105 cm−2 (one order of magnitude as compared to the dislocation density of the Ge/Si PS). The optical properties are improved (ie. increased photoluminescence intensity). Using ALE, light emitting diodes based on strained InGaAs/GaAs quantum well as well as of In(Ga)As quantum dots on an exactly oriented (001) Ge/Si pseudo-substrate were fabricated and characterized.