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Type-I InAs quantum wells have been grown on metamorphic In0.83Al0.17As buffers on (0 0 1)-oriented GaP and InP substrates by gas source molecular beam epitaxy. The structural and optical properties as well as strain conditions were characterized and investigated to compare the material quality of samples grown on GaP and InP substrates, respectively. Photoluminescence up to 2.8 μm has been observed for the quantum wells at room temperature. The quantum wells on GaP and InP show the similar photoluminescence intensity, X-ray diffraction peaks and Raman shift performances. These results indicate the potential to demonstrate type-I mid-infrared light sources on Si substrate using GaP as a template.

In this study we show how to realize a self-assembled nano-patterned sapphire surface on 2 inch diameter epi-ready wafer and the subsequent AlN overgrowth both in the same metal-organic vapor phase epitaxial process. For this purpose in-situ annealing in H 2 environment was applied prior to AlN growth to thermally decompose the c-plane oriented sapphire surface. By proper AlN overgrowth management misoriented grains that start to grow on non c-plane oriented facets of the roughened sapphire surface could be overcome. We achieved crack-free, atomically flat AlN layers of 3.5 µm thickness. The layers show excellent material quality homogeneously over the whole wafer as proved by the full width at half maximum of X-ray measured ω-rocking curves of 120 arcsec to 160 arcsec for the 002 reflection and 440 arcsec to 550 arcsec for the 302 reflection. The threading dislocation density is 2 ∗ 10 9 cm −2 which shows that the annealing and overgrowth process investigated in this work leads to cost-efficient AlN templates for UV LED devices.

In this study, secondary ion mass spectroscopy of oxygen, deep level transient spectroscopy and power dependent relative photoluminescence are compared regarding their ability to resolve differences in Al x Ga 1−x As material quality. Al x Ga 1−x As samples grown with two different trimethylaluminum sources showing low and high levels of oxygen contamination are compared. As tested in the growth of minority carrier devices, i.e. Al x Ga 1−x As solar cells, the two precursors clearly lead to different device characteristics. It is shown that secondary ion mass spectroscopy could not resolve the difference in oxygen concentration, whereas deep level transient spectroscopy and photoluminescence based measurements indicate the influence of the precursor oxygen level on the material quality.

We investigate growth conditions to obtain high-quality SiC bulk crystals by the High-Temperature Chemical Vapor Deposition (HTCVD) method. Formation of dendrite crystals, which sometimes occurs on the growth front and degrades the material quality, is raised as an issue. We find that a bulk crystal growth under a high vertical temperature gradient, where the temperature of the back side of the bulk crystal is much lower than that of the crystal surface, suppresses the formation of dendrite crystals. Under growth conditions with a high temperature gradient, a very high-speed growth of 2.4 mm/h is achieved without the formation of dendrite crystals. Growth of a thick 4H–SiC bulk crystal without the dendrites is demonstrated and the quality of a grown crystal is evaluated.

Growth of efficient III-N based light emitting devices by plasma assisted molecular beam epitaxy has been elusive, even though the technique has attractive advantages in comparison to metal organic chemical vapor deposition. Modern high-flux radio frequency plasma systems could remedy this issue by enabling growth of InxGa1-xN at higher temperatures than previously possible, likely improving the material quality. In this work, active nitrogen fluxes of up to 3.5 μm/h GaN-equivalent growth rate were employed to grow InxGa1-xN alloys. InxGa1-xN growth rates of 1.3 μm/h were demonstrated at growth temperatures of 550 °C and 600 °C with maximum film compositions of In0.25Ga0.75N and In0.21Ga0.79N, respectively. A composition of In0.05Ga0.95N was observed in a film grown at 700 °C with smooth step-terrace morphology.

Epitaxial films of AlN were grown on a sapphire substrate with a miscut of 0.38°±0.02° towards the m-plane by metalorganic vapour phase epitaxy. A low temperature nucleation layer was used to overcome growth instabilities and to suppress the formation of inversion domains. This was followed by high temperature growth at 1250 °C. This two-step process, gives an acceptable material quality, (0002 FWHM=398±10′′ and 10–11 FWHM=940±23′′), but resulted in a top surface dominated by large steps, with average heights of 6.0±0.5 nm. Atomic force microscopy analysis of step termination sites shows a staircase of single and double atomic steps, showing large steps are formed by the bunching of single steps, perhaps pinned by threading dislocations. To achieve a smooth top surface, 100 nm of the high temperature AlN is followed by growth at 1110 °C. This three step process largely eliminates the large steps resulting in a layer that has a smooth surface morphology and lower defect density (0002 FWHM=351±9′′ and 10–11 FWHM=761±19′′).

Lattice-mismatched heteroepitaxial growth in compound semiconductor layer structures, e.g. metamorphic buffers, is frequently used to combine materials with favorable properties. A detailed understanding of the strain relaxation during growth is important to optimize the buffer layers and to achieve high material quality. We present a method to determine the epilayer relaxation at growth temperature from room temperature X-ray diffraction measurements. For this the lattice parameters are measured with (004) and (224) reciprocal space maps along two orthogonal directions to account for anisotropic misfit strain relaxation. Dissimilar thermal expansion coefficients of substrate and epilayer are taken into consideration when calculating the lattice parameters and epilayer relaxation parameters at growth temperature. The application of this method is discussed for GaAs x P 1− x metamorphic buffer structure on Si with eight lattice-mismatched layers showing a relaxation parameter of over 130% at room temperature. All layers were found to be nearly 100% relaxed at growth temperature. The use of this method for other compound semiconductors is discussed.

GaN boules were grown up to thicknesses of 6.3 mm via vertical HVPE on 2 in. GaN/sapphire templates. The usable boule length is limited by surface defects. Two different sub-surface disturbances were identified to be responsible for these surface defects using optical inspection and low-temperature photoluminescence on polished m -plane slices cut from the boules. One disturbance starts already at the interface to the used template resulting in large V-pits at the surface. The other one occurs after undisturbed GaN growth of several mm and leads to local cracking networks and small V-pits at the surface. Both lead to deteriorated structural properties of subsequently grown material with red-shifted and broadened exciton emission. In contrast, the undisturbed material having a smooth surface is of high material quality and shows constant energies of the exciton emissions with narrow line widths.

This report concentrates on a few selected electronic properties of III-nitrides, and illustrates the large uncertainties in the physical quantities that exist. A considerable improvement in material quality, in terms of both structural and point defect densities, is needed before more reliable data can be obtained.

The lattice mismatched MOVPE growth of In 0.82 Ga 0.18 As and InAs 0.61 P 0.39 is described. A study of the influence of the InGaAs growth temperature results in an optimum around 590°C. Also the influence of the buffer layer on the material quality (X-ray FWHM) is reported. Since these materials are intended for the fabrication of photodetectors in the 2.4 μm region, also the etch behaviour and Zn diffusion (inside MOVPE reactor) are reported.

We report gas-source molecular beam epitaxial growth of highly strained InxGa1−xPGaP quantum wells on GaP and on an Inx2Ga1−x2P buffer layer. High-resolution X-ray diffraction and photoluminescence (PL) have been used to characterize the material quality. Satellite peaks up to ±2nd order are observed from a 50 period InxGa1−xP(50 A)GaP(50 A) multiple quantum well (MQW) grown on an Inx2Ga1−x2P buffer layer, whereas only the 1st-order satellite peak is observed for the same structure grown directly on GaP under the same growth condition, which indicates better-quality InxGa1−xPGaP MQWs can be achieved by using an Inx2Ga1−x2P buffer layer. Furthermore, an increase in the X-ray satellite peak intensity of the InxGa1−xPGaP MQWs grown on the Inx2Ga1−x2P buffer layer has been observed as the period of the MQW increases, suggesting no structural degradation and an increase of the critical layer thickness of the MQWs. PL measurements also show that an Inx2Ga1−x2P buffer layer is effective in improving the optical quality of the InxGa1−xPGaP MQWs.

An automatic X-ray double diffractometry technique for SOS characterization is presented. With this technique it is possible to quickly obtain an evaluation of the crystalline quality of the deposited silicon layer. Therefore it can be used for systematic evaluation of material quality. A more detailed analysis can also give the profile of dislocations in the silicon layer. This profile has been correlated with Rutherford backscattering spectra.

The possibility of growing GaP on Si with good electrical and optical properties would enable the realization of interesting devices. An investigation of microscopical, electrical and optical properties of GaP grown on Si substrates by MOVPE is presented, with special emphasis on defect characterization. Net carrier concentrations of 5×10 15 cm -3 have been achieved, i.e. an order of magnitude lower than those previously reported. Deep electron traps studied in the GaP material have been investigated by DLTS and are observed in concentrations below 2×10 13 cm -3 . Low temperature photoluminescence measurements show bound excitons and donor-acceptor pair bands from which the incorporation of background impurities and the material quality are judged.

This review is concerned with developments that have taken place over the last year or so in the field of metalorganic vapour phase epitaxy of II–VI compounds. In this rapidly developing field the compounds attracting most study are CdTe, CdxHg1−xTe, HgT e, ZnSe, ZnSxSe1−x, ZnS, CdS and ZnO. These developments, which are considered within the framework of existing knowledge, cover organic reagents or precursors, alternative substrates, reaction mechanisms and developments in growth technique. Prominence is given to Photo-MOVPE and low temperature growth. Improvements in material quality and recent device advances using MOVPE are also reported.

This paper describes, for the first time, the development of atmospheric pressure MOVPE growth for the large scale production of InP based opto-electronic devices. Results are presented on material quality, large area uniformity, device performance, yield and reliability, both in an R&D environment and in the production facility to demonstrate that InP based MOVPE technology has now made the crucial transition from the research and development area into large scale production.