Strain relaxation of InP film directly grown on GaAs patterned compliant substrate

In order to overcome the large lattice mismatch in the heteroepitaxy, a new patterned compliant substrate method has been introduced, which has overcome the disadvantages of previously published methods. InP film of thickness 800 nm was directly grown on this substrate. Scanning electron microscopy (SEM) has shown that good surface morphology has been obtained. In addition, Photoluminescence (PL) and double crystal X-ray diffraction (DCXRD) study have shown that the residual strain has been reduced, and that the structure quality has been improved. (C) 2002 Elsevier Science B.V. All rights reserved.

In situ doping of 3C-SiC grown on (0001) sapphire substrates by LPCVD

The heteroepitaxial growth of n-type and p-type 3C-SiC on (0001) sapphire substrates has been performed with a supply of SiH4+C2H4+H-2 system by introducing ammonia (NH3) and diborane (B2H6) precursors, respectively, into gas mixtures. Intentionally incorporated nitrogen impurity levels were affected by changing the Si/C ratio within the growth reactor. As an acceptor, boron can be added uniformly into the growing 3C-SiC epilayers. Nitrogen-doped 3C-SiC epilayers were n-type conduction, and boron-doped epilayers were p-type and probably heavily compensated.

ECR plasma in growth of cubic GaN by low pressure MOCVD

To heteroepitaxally grow the crystalline cubic-GaN (c-GaN) film on the substrates with large lattice mismatch is basically important for fabricating the blue or ultraviolet laser diodes based on cubic group III nitride materials. We have obtained the crystalline c-GaN film and the heteroepitaxial interface between c-Gan and GaAs (001) substrate by the ECR Plasma-Assisted Metal Organic Chemical Vapor Deposition (PA-MOCVD) under low-pressure and low-temperature (similar to600degreesC) on a homemade ECR-plasma Semiconductor Processing Device (ESPD). In order to decrease the growth temperature, the ECR plasma source was adopted as the activated nitrogen source, therefore the working pressure of MOCVD was decreased down to the region less than 1 Pa. To eliminate the damages from energetic ions of current plasma source, a Multi-cusp cavity,coupling ECR Plasma source (MEP) was selected to use in our experiment. To decrease the strain and dislocations induced from the large lattice mismatch between c-GaN and GaAs substrate, the plasma pretreatment procedure i.e., the initial growth technique was investigated The experiment arrangements, the characteristics of plasma and the growth procedure, the characteristics on-GaN film and interface between c-GaN and GaAs(001), and the roles of ECR plasma are described in this contribution.

The growth of SiC on Si substrates with C2H4 and Si2H6

SiC was grown on Si (100) substrates oriented and off-oriented by 2-5 degrees towards [011] with simultaneous supply of C2H4 and S2H6 at 1050 degrees C. SiC formed during removal of oxide could be removed at 1150 degrees C. Twinned growth occurred on both oriented and off-oriented substrates during carbonization, but fewer twins formed on the off-oriented substrate than that on the oriented substrate. In SiC growth process, twinned growth continued on the off-oriented substrate whereas twinned growth stopped and single crystal SiC with double-domain (2 x 1) superstructure formed on the oriented substrate. SiC single crystal could grow on a carbonized twinned buffer layer. Obvious SiC LO and TO phonon modes were observed with Raman spectroscopy in the epilayer grown on the oriented substrate. The surface of the epilayer grown on the oriented substrate was smooth, while there was a high density of islands on the epilayer grown on the off-oriented substrate. The film grown on the oriented substrate is superior than that grown on the off-oriented substrate. (C) 1999 Elsevier Science B.V. All rights reserved.

The effects of carbonized buffer layer on the growth of SiC on Si

Carbonized buffer layers were formed with C2H4 on Si(100) and Si(111) substrates using different methods and SIC epilayers were grown on each buffer layer at 1050 degrees C with simultaneous supply of C2H4 and Si2H6. The structure of carbonized and epitaxy layers was analyzed with in situ RHEED. The buffer layers formed at 800 degrees C were polycrystalline on both Si(100) and Si(111) substrates whereas they were single crystals, with twins on Si(100) and without tu ins on Si(111)substrates. when formed with a gradual rise in substrate temperature from 300 degrees C to growth temperature. Raising the substrate temperature slowly results in the formation of more twins. Epilayers grown on carbonized polycrystalline lavers are polycrystalline. Single crystal epilayers without twins grow on single crystalline buffer layers without twins or with a few twins. (C) 1999 Elsevier Science B.V. All rights reserved.

Evolution of height distribution of Ge islands on Si(1 0 0)

Evolution of the height distribution of Ge islands during in situ annealing of Ge films on Si(1 0 0) has been studied. Island height is found to have a bimodal distribution. The standard deviation of the island height divided by the mean island height, for the mode of larger island size is more than that for the other mode. We suggest that the presence of Ehrlich-Schwoebel barriers, combined with the misfit strain, can lead to the bimodal distribution of island size, the mode of larger island size having narrower base size distribution, but wider height distribution for Ge islands on Si(1 0 0). The bimodal distribution of island size could be stable due to kinetics without necessarily regarding it as minimum-energy configuration. (C) 1999 Elsevier Science B.V. All rights reserved.

GROWTH OF HIGH-QUALITY GALLIUM-ARSENIDE ON HF-ETCHED SILICON (001) BY CHEMICAL BEAM EPITAXY

HF etching followed by relatively low temperature (almost-equal-to 600-degrees-C) pretreatment is shown to provide a suitable substrate for the heteroepitaxial growth of GaAs on Si(100) by CBE using TEGa and AsH3 as sources. Rutherford backscattering (RBS), photoluminescence (PL), transmission electron microscopy (TEM), and Raman measurements show the low-defect nature of the GaAs epilayer.

A theoretical model for the tilt of the GaAs/Si epilayers

The crystallographic tilt of the epilayers with respect to their substrates has been observed in many heteroepitaxial systems. Many models have been proposed to explain this phenomenon, but none of them is suitable for the large mismatched system, such as GaAs/Si. Here a new model is proposed for GaAs/Si epilayers, which can also be used in other large mismatched systems. The magnitude of the tilt calculated from this model coincide well with the experimental results. Especially, this model can correctly predict the tilt direction of the GaAs/Si epilayers.

X-ray-diffraction study of quasipseudomorphic ErSi1.7 layers formed by channeled ion-beam synthesis

ErSi1.7 layers with high crystalline quality (chi(min) of Er is 1.5%) have been formed by 90 keV Er ion implantation to a dose of 1.6X10(17)/cm(2) at 450 degrees C using channeled implantation. The perpendicular and parallel elastic strain e(perpendicular to)=-0.94%+/-0.02% and e(parallel to)=1.24%+/-0.08% of the heteroepitaxial erbium silicide layers have been measured with symmetric and asymmetric x-ray reflections using a double-crystal x-ray diffractometer. The deduced tetragonal distortion e(T(XRD))=e(parallel to)-e(perpendicular to)=2.18%+/-0.10%, which is consistent with the value e(T(RBS))2.14+/-0.17% deduced from the Rutherford backscattering and channeling measurements. The quasipseudomorphic growth of the epilayer and the stiffness along a and c axes of the epilayer deduced from the x-ray diffraction are discussed.

INPLANE X-RAY-SCATTERING OF EPITAXIAL STRUCTURES

A new approach for in-plane X-ray scattering from the cleavages of epitaxial films or superlattices, where the scattering vectors are parallel to the interfaces, is proposed. This method can be employed to determine directly the in-plane X-ray strains and other atomic registry along the interfaces of the epitaxial structures.

Twinning in Low-Temperature MOCVD Grown GaN on (001) GaAs Substrate

GaN buffer layers (thickness ～60nm) grown on GaAs(001) by low-temperature MOCVD are investigated by X-ray diffraction pole figure measurements using synchrotron radiation in order to understand the heteroepitaxial growth features of GaN on GaAs(001) substrates. In addition to the epitaxially aligned crystallites,their corresponding twins of the first and the second order are found in the X-ray diffraction pole figures. Moreover, { 111 } q scans with χ at 55° reveal the abnormal distribution of Bragg diffractions. The extra intensity maxima in the pole fig ures shows that the process of twinning plays a dominating role during the growth process. It is suggested that the polarity of { 111 } facets emerged on (001) surface will affect the growth-twin nucleation at the initial stages of GaN growth on GaAs(001) substrates. It is proposed that twinning is prone to occurring on { 111 } B, N-terminated facets.

Improvement of CMOS SOS devices characteristics by a modified solid phase epitaxy

CMOS/SOS devices have lower carriers mobility and higher channel leakage current than bulk silicon CMOS devices. These mainly results from the defects of heteroepitaxial silicon film, especially from the defects near Si-Sapphire interface. This paper describes the experiment results of CMOS/SOS devices characteristics improved by a better epitaxial silicon quality which is obtained by a modified solid phase epitaxy.

In situ doping of 3C-SiC grown on (0001) sapphire substrates by LPCVD

The heteroepitaxial growth of n-type and p-type 3C-SiC on (0001) sapphire substrates has been performed with a supply of SiH4+C2H4+H-2 system by introducing ammonia (NH3) and diborane (B2H6) precursors, respectively, into gas mixtures. Intentionally incorporated nitrogen impurity levels were affected by changing the Si/C ratio within the growth reactor. As an acceptor, boron can be added uniformly into the growing 3C-SiC epilayers. Nitrogen-doped 3C-SiC epilayers were n-type conduction, and boron-doped epilayers were p-type and probably heavily compensated.

The effects of carbonized buffer layer on the growth of SiC on Si

Carbonized buffer layers were formed with C2H4 on Si(100) and Si(111) substrates using different methods and SIC epilayers were grown on each buffer layer at 1050 degrees C with simultaneous supply of C2H4 and Si2H6. The structure of carbonized and epitaxy layers was analyzed with in situ RHEED. The buffer layers formed at 800 degrees C were polycrystalline on both Si(100) and Si(111) substrates whereas they were single crystals, with twins on Si(100) and without tu ins on Si(111)substrates. when formed with a gradual rise in substrate temperature from 300 degrees C to growth temperature. Raising the substrate temperature slowly results in the formation of more twins. Epilayers grown on carbonized polycrystalline lavers are polycrystalline. Single crystal epilayers without twins grow on single crystalline buffer layers without twins or with a few twins. (C) 1999 Elsevier Science B.V. All rights reserved.

Monte Carlo simulation of properties of monolayers and metal islands adsorbed on metallic (111) surfaces

To obtain the surface stress changes due to the adsorption of metal monolayers onto metallic surfaces, a new model derived from thermodynamic considerations is presented. Such a model is based on continuum Monte Carlo simulations with embedded atom method potentials in the canonical ensemble, and it is extended to consider the behavior on different islands adsorbed onto (111) substrate surfaces. Homoepitaxial and heteroepitaxial systems are studied. Pseudomorphic growth is not observed for small metal islands with considerable positive misfit with the substrate. Instead, the islands become compressed upon increase of their size. A simple model is proposed to interpolate between the misfits of atoms in small islands and the pseudomorphic behavior of the monolayer.