Investigation of Ge and C layer deposition on a Si substrate using SIMS profiling

Structures grown using the technique of molecular-beam epitaxy during deposition of carbon and/or germanium atoms on an Si(111) surface were investigated experimentally and theoretically. Experimental profiles of in-depth component distribution were obtained using SIMS-profiling, whereas a complex technique of computer simulation taking into account diffusion and ballistic processes was applied for the calculated profiles.     

Surface morphology of Ge‐modified 3C‐SiC/Si films

The influence of Ge deposition prior to carbon interaction with 3° off‐axis Si(111) substrates on the structural and morphological properties of the formed silicon carbide (SiC) layer is studied. In situ reflection high‐energy electron diffraction (RHEED) and X‐ray diffraction (XRD) revealed the formation of the cubic silicon carbide (3C‐SiC) modification. In situ spectroscopic ellipsometry measurements revealed a decreasing 3C‐SiC thickness with increasing Ge predeposition. Atomic force microscopy (AFM) studies revealed that the surface overlayer morphology is mainly formed by periodic step arrangements whose relevant geometric parameters, i.e. lateral separation, height and terrace width, depend on the Ge content. Besides the changes of the step morphology, the surface roughness and the grain size and the strain of the formed 3C‐SiC decreases with increasing germanium precoverage. Copyright © 2008 John Wiley & Sons, Ltd.     

SiC polytypes process affected by Ge predeposition on Si(111) substrates

Structural and optical measurements were performed on silicon carbide (SiC) samples containing several polytypes. The SiC samples investigated were grown on (111) Si substrates by solid source molecular beam epitaxy (SSMBE). Several quantities of Ge were predeposited before the growth procedure. The influence of Ge on the SiC polytypes formation was studied by X-Ray, FTIR and μ-Raman characterizations methods. The spectra of the samples with less than one Ge monolayer exhibit a mixture of 2H, 15R and 3C–SiC polytypes. This mixture is due to the mismatch between the heterostructure layers. We propose that the Ge predeposition in the heterostructure can be used to stabilize and unify the polytypes formation.     

5 μm thick 3C-SiC layers grown on Ge-modified Si(100) substrates

The effect of the germanium coverage prior to the epitaxial growth of 5 μm thick 3C-SiC on Si(100) substrates were evaluated with Atomic Force Microscopy and μ-Raman spectroscopy. The 3C-SiC layers were grown by atmospheric pressure chemical vapor deposition via a special procedure leading to layers with compressive instead of tensile stress. The Ge amount was varied from 0 up to 2 ML. The obtained results showed that the residual stress inside the layers is shifted in the compressive direction; the crystalline quality is improved with the Ge introduction but on the account of the surface roughness. These results open the route for the use of Ge-modified Si(100) as a potential substrate in order to improve the heteroepitaxial growth of 3C-SiC on silicon substrates.     

Interpretation of Auger depth profiles of thin SiC layers on Si

Silicon carbide thin films, prepared by carbonization of Si-wafers are analysed by Auger depth profiling. The influence of atomic mixing is simulated with a Monte Carlo model. By using mixing simulations the dependence of the two mixing parameters (width of the mixing zone and recoil depth) on ion beam energy, incidence angle and ion mass can be calculated. For comparison of the simulated data with Auger measurements an Auger electron escape depth correction is necessary. The simulated and -corrected data of several layer structures show good qualitative agreement with Auger depth profiles of thin carbonized SiC-layers.Dedicated to Professor Dr. rer. nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthday     

The influence of ion beam sputtering on the composition of the near-surface region of silicon carbide layers

The concentrations and the lattice structure of silicon carbide layers and single crystals are influenced by ion beam sputtering. The influence of ion beam sputtering and primary ion energy on preferential sputtering is investigated by Auger measurements and T-DYN simulations. In dependence on primary ion energy C is enriched. Preferential sputtering increases with decreasing ion energy. Sputtering has a strong influence on the Auger peak shapes of SiC. Except for low ion energy and glancing incidence the peak shapes are independent of the primary ion energy. T-DYN simulations help to explain and understand the near-surface processes during sputtering of SiC. For ion energy dependence of preferential sputtering there is a good agreement of the T-DYN simulation and the Auger measurement. Received: 10 October 1998 / Revised: 26 March 1999 / Accepted: 2 April 1999     

Impurity Effects on Nucleation and Growth of SiC Clusters and Layers on Si(100) and Si(111)

Physics of the Solid State - A kinetic Monte Carlo model of silicon carbide growth on silicon surface is proposed. Based on this model, the growth of silicon carbide clusters on silicon in the...     

Cubic InN on -plane sapphire

InN has been grown directly on r-plane sapphire substrates by plasma-induced molecular beam epitaxy. X-ray diffraction and transmission electron microscopy investigations have shown that the InN layers consist of a predominant zinc-blende (cubic) structure along with a fraction of the wurtzite (hexagonal) phase whose content increases with proceeding growth. The InN layer is defect rich with a high number of stacking faults and twins. As a consequence a very high residual doping of was estimated. The lattice constant for the zinc-blende phase of InN was found to be a=4.986 Å. The optical investigations were strongly affected by a high number of defects, but nevertheless indicated an absorption edge below 0.6 eV. For this unusual growth of the metastable cubic phase on a noncubic substrate an epitaxial relationship was proposed, where the metastable zinc-blende phase grows directly on the r-plane of sapphire.     

Determination of strain and composition in SiC/Si and AlN/Si heterostructures by FTIR-ellipsometry

Heteroepitaxially grown 3C-SiC and 2H-AlN layers on Ge modified Si(111) substrates were investigated by Fourier transform infrared spectroscopic ellipsometry. The obtained phonon frequencies increase with increasing Ge pre-deposition indicating a decrease of the residual stress in both wide band gap materials. Additionally, it is shown that infrared ellipsometry allows the analysis of the polytype content of the grown epitaxial layers.     

Study of Si and C adatoms and SiC clusters on the silicon surface by the molecular dynamics method

Individual Si and C adatoms, as well as SiC clusters, on a Si surface are simulated by the molecular dynamics method in the course of investigation of the initial stages of formation of a SiC layer on silicon with the help of molecular beam epitaxy. The potential energy surfaces for Si and C adatoms on the (2 × 1) reconstructed Si(001) surface and on the nonreconstructed Si(111) surface, as well as on the Si(111) surface with a SiC cluster, are calculated and analyzed. The values of migration barriers for adatoms on these surfaces are calculated. The effect of the SiC cluster on deformation of the surface region of Si(111) and on the migration of adatoms is investigated. The deep minima observed on the potential energy surfaces immediately above a cluster and at its boundaries can trap diffusing adatoms. The distributions of stresses and strains in the silicon lattice under a cluster on the surface are studied and described.