Synchrotron x-ray topographic and high-resolution diffraction analysis of mask-induced strain in epitaxial laterally overgrown GaAs layers

Synchrotron x-ray back reflection section topographs of epitaxial lateral overgrown (ELO) GaAs samples grown on (001) GaAs substrates show images of the GaAs layers bent due to the interaction between the layer and the SiO2 mask. The topographs are simulated under the assumption of orientational contrast. Using the same data the measured x-ray diffraction curve is simulated. The calculations, which are in good agreement with the measurements, are used to gain information on the tilted (001) lattice planes in each ELO layer. We show that the bending of ELO lattice planes reaches a maximum at the center of the ELO stripes, where misorientation is at a minimum, and decreases towards the edges of the stripes, where misorientation reaches a maximum

Photoinduced defects creation on sulfur passivated surface of GaAs

We report on photoinduced defect creation on the sulfurized (100) GaAs surface. The process manifests itself by unrecoverable temporal decrease in the photoluminescence intensity of the GaAs surface treated by (NH4)2Sx solution. The results are discussed in terms of a photoinduced process of the AsGa antisite generation on the sulfurized surface of GaAs.Peer Reviewe

Epitaxial Lateral Overgrowth - a Tool for Dislocation Blockade in Multilayer Systems

Results on epitaxial lateral overgrowth of GaAs layers are reported. The methods of controlling the growth anisotropy, the effect of substrate defects filtration in epitaxial lateral overgrowth procedure and influence of the mask on properties of epitaxial lateral overgrowth layers will be discussed. The case of GaAs epitaxial lateral overgrowth layers grown by liquid phase epitaxy on heavily dislocated GaAs substrates was chosen as an example to illustrate the processes discussed. The similarities between our results and those reported recently for GaN layers grown laterally by metallorganic vapour phase epitaxy will be underlined

Electroepitaxial Growth of GaSb and AlGaSb Thick Epitaxial Layers

Semi-bulk epitaxial layers of GaSb and AlGaSb up to 3 and 1 mm thick, respectively, were successfully grown by the liquid phase electroepitaxy on GaSb substrates. The growth procedure allowed us to achieve high crystallographic perfection as well as compositional uniformity of ternary layers

High-temperature ultraviolet detection based on surface photovoltage effect in SiN passivated n-GaN films

We investigated the surface photovoltage (SPV) effect in n-GaN layers passivated with various insulators, i.e., Al2O3, SiO2, and SiN for ultraviolet (UV) light detection. We revealed that SPV in SiN/GaN shows markedly different behaviour than in oxide/GaN, i.e., the photo-signal exhibited very fast response (1 s) and recovery (2 s) times, contrary to oxide/GaN, and it was thermally stable up to 523 K. Furthermore, SPV spectra for SiN/GaN showed a sharp cut-off edge directly corresponding to the GaN band gap. We explained these results in terms of the different band structure of SiN/GaN and oxide/GaN junctions. All the observed properties of SPV response from SiN/GaN indicate that this relatively simple system can be applied to sensitive high temperature visible-blind UV detection. Published by AIP Publishing

Spatially Resolved X-ray Diffraction Technique for Crystallographic Quality Inspection of Semiconductor Microstructures

Spatially resolved X-ray diffraction is introduced and applied for micro-imaging of strain in GaAs and GaSb layers grown by epitaxial lateral overgrowth on GaAs substrates. We show that laterally overgrown parts of the layers (wings) are tilted towards the underlying mask. By spatially resolved X-ray diffraction mapping the direction of the tilt and distribution of tilt magnitude across the width of each layer can be readily determined. This allows measuring of the shape of the lattice planes in individual epitaxial stripes. In GaSb/GaAs heteroepitaxial laterally overgrown layers local mosaicity in the wing area was found. By spatially resolved X-ray diffraction the size of microblocks and their relative misorientation were analyzed. Finally, microscopic curvature of lattice planes confined between two neighboring slip bands in thermally strained Si wafers is measured. All these examples show advantages of spatially resolved X-ray diffraction over a standard X-ray diffraction when applied for analysis of crystalline microstructures

Rocking Curve Imaging Studies of Laterally Overgrown GaAs and GaSb Epitaxial Layers

X-ray rocking curve imaging technique was used to study crystallographic perfection of laterally overgrown epitaxial structures. We focus on rocking curve imaging studies of Si-doped GaAs and GaSb laterally overgrown layers grown by liquid phase epitaxy on $SiO_{2}$ masked GaAs and GaSb/GaAs substrates, respectively. High spatial resolution offered by rocking curve imaging technique allows studying the effect of laterally overgrown epitaxial wing tilt towards the mask. Distribution of tilt magnitude over the area of laterally overgrown epitaxial stripes is easily determined. In heteroepitaxial GaSb/GaAs laterally overgrown epitaxial structures local mosaicity in the wing area was detected. Since individual grains are clearly visible on rocking curve imaging maps, their size and relative misorientation can be determined