We observed the coexistence of two types of ordered structures, Cu3Au and CuPt, in Zn0.4Fe0.6Se epilayers grown on ZnSe buffer layers on (001) GaAs substrates by transmission electron microscopy. In addition, the Cu3Au ordered structure exists with a multi-faceted domain shape. Energy dispersive x-ray spectra from these domains showed higher Fe concentration than in the disordered matrix. However, in Zn0.5Fe0.5Se epilayers, we only observed CuAu-I ordered multi-faceted domains. The samples with relatively high Fe concentration (x ≈0.6) also showed domains of FeSe with a hexagonal structure with triangular form coexisting with Cu3Au ordered domains. Strain-induced interdiffusion takes place between the buffer layer and the epilayer as evidenced by a rough interface between the alloy and the buffer layer.

We report on the effectiveness of proximity caps and PECVD Si3N4 caps during annealing of implanted ZnSe films. OMVPE ZnSe films were grown using diisopropylselenide (DIPSe) and diethylzinc (DEZn) precursors, then ion-implanted with 1 × 1014 cm−2 N (33 keV) or Ne (45 keV) at room temperature and liquid nitrogen temperature, and rapid thermal annealed at temperatures between 200°C and 850°C. Rutherford backscattering spectrometry in the channeling orientation was used to investigate damage recovery, and photoluminescence spectroscopy was used to investigate crystal quality and the formation of point defects. Low temperature implants were found to have better luminescence properties than room temperature implants, and results show that annealing time and temperature may be more important than capping material in determining the optical properties. The effects of various caps, implant and annealing temperature are discussed in terms of their effect on the photoluminescence spectra.

CVD is applied to grow the multilayer structure on CdSe proposed as a promising coating for IR-optics. The coating is composed of alternately grown CdS and CdSe single crystal layers. The proposed coating characteristics are expected to be much better than those of the coatings produced by the sputtering method.

Significant progress has been made in HgCdTe MBE technology over the last two years. Device quality materials have been grown with the alloy compositions required for short-wavelength infrared (SWIR), 1-3 micron to LWIR (long-wavelength infrared), 8-12 micron applications. Indeed, the observation of low defect density (EPD<2×105/cm2), long minority carrier lifetime and efficient IR photoluminescence attests to the device quality of HgCdTe epilayers grown by MBE. In addition, the breakthroughs to achieve In (N-type) and As (P-type) doping in situ have provided greater flexibilities for fabricating advanced heterojunction devices. High performance IR imaging arrays have been fabricated and IR images were obtained. Also, dual-band detectors and injection infrared diode lasers which have been demonstrated recently are considered. Finally, additional developments and the future challenges in HgCdTe MBE technology are discussed.

We report for the first time the results of structural and optical characterizations performed on Mercury Cadmium Telluride (MCT) grown simultaneously by Molecular Beam Epitaxy (MBE) on (11 1)B 4°misoriented and (211)B CdZnTe substrates. These two Te-terminated surfaces differ only by the density and the nature of their surface steps. In MBE conditions we do not observe any difference of incorporation between the two orientations at low growth temperatures and only a slight difference in Te and Hg incorporations above 200°C. This study confirms that the growth mode is essentially the same on both orientations and the growth proceeds by step-flow. The higher step density on (211) surfaces allows broader tolerances on the substrate temperature for the growth of twin-free material. It also leads to higher crystalline quality for the lowest temperatures. These observations have been confirmed by magneto-absorption experiments on superlattices grown simultaneously on both orientations.

A TEM study of the initial nucleation layers for the two-step growth of CdTe on 2°-off (001) GaAs substrates by MOCVD is presented. When the substrates are degreased and etched in the usual manner, the initial deposits are oriented with their axes parallel to those of the substrates. When the substrates are, instead, prepared by thermal etching at 545-585°C, the initial deposits contain both (001) and (111)-oriented grains. When these polycrystalline initial deposits are heated to the “bulk” growth temperature, epitaxial regrowth occurs giving a single crystal film with a very distinctive anisotropic defect microstructure. Possible reasons for these effects are discussed.

The enhanced Zeeman effect of excitons in asymmetric CdZnTe-CdTe-CdMnTe quantum wells is studied quantitatively to gain information separately on the profile of the normal and inverted interfaces. The normal interface appears as more “abrupt” than the inverted interface. This behaviour is well accounted for if we assume that during the growth a rapid Cd/Mn exchange takes place between the surface layer and the subsurface one.

A thermodynamic analysis of the vapour phase species occurring in the undoped CdTe and doped CdTe:X (X = Cl, Br, I) systems is given. Calculations are performed using a Gibbs energy minimizer software (EPC), which offers the possibility of receiving relativly prompt results allowing for the change in experimental conditions as well as the consideration of even spurious species.

In each system, the dopant - transporting species are the cadmiumdihalogenides CdX2. Contrary, in the CdTe:I vapour phase two more species (Tel and I) have to be considered at the growing phase boundary afffecting transport and interface kinetics.

Epitaxial growth of the ordered vacancy compound (OVC) CuIn3Se5 has been achieved on GaAs (100) by molecular beam epitaxy (MBE) from Cu2Se and In2Se3 sources. Electron probe microanalysis and X-ray diffraction have confirmed the composition for the 1-3-5 OVC phase and that the film is single crystal Culn3Se5 (100). Transmission electron microscopy (TEM) characterization of the material also showed it to be single crystalline. Structural defects in the layer consisted mainly of stacking faults. Photoluminescence (PL) measurements performed at 7.5 K indicate that the bandgap is 1.28 eV. Raman spectra reveal a strong polarized peak at 152 cm−1, which is believed to arise from the totally symmetric vibration of the Se atoms in the lattice. Atomic force microscopy reveals faceting in a preferred (100) orientation.