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We report on the growth of monocrystalline thin films of ZnSe and ZnO by atomic layer epitaxy by simple reaction between elemental precursors. Structural and optical properties of these films are discussed with reference to the investigations performed with atomic force microscopy, scanning electron microscopy, cathodoluminescence and photoluminescence.

Thin films of sphalerite-type ZnSe were grown by atomic layer deposition (ALD) from elemental Zn and Se precursors. These films, grown on various substrates, show bright blue ‘edge’ emission accompanied by donor–acceptor pair emissions in the blue, green and red spectral regions. Red, green and blue emissions mixed together give a white color, with a color temperature between 2400 and 4500 K depending on a layer thickness and temperature. ZnSe grown by ALD is in consequence a promising material for the fabrication of semiconductor-based white light emitting thin film electroluminescence displays.

We discuss light emission properties from thin films of ZnSe grown by atomic layer epitaxy on GaAs (100). White color emission is observed in photoluminescence and cathodoluminescence, due to the observation of three RGB emission bands. We demonstrate possibility of color tuning by either variation of film thickness or, in cathodoluminescence experiments, variation of an accelerating voltage. © 2002 Elsevier Science B.V. All rights reserved.

We have investigated deep-level defects in InGaAsN/GaAs 3xQW structures by means of conventional as well as high-resolution deep level transient spectroscopy (DLTS). The three samples were grown by atmospheric pressure metalorganic vapour phase epitaxy (AP-MOVPE) in different growth temperatures (566°C, 575°C and 585°C). The DLTS measurements revealed four electron traps E1 (0.17-0.24 eV), E2 (0.36-0.38 eV), E3 (0.46-0.49 eV) and E4 (0.81-0.84 eV) and one hole trap H1(0.8 eV) in our structures. The electron trap E1 was associated with N-related complexes while the other electron traps with native defects, usually observed in GaAs-based structures EL6, EL3 and EL2, respectively. Finally, the trap E2 and H1, observed in the structure grown at lowest temperature, were associated with the same trap, which can act as both an electron and hole trap. It was thus concluded that E2/H1 may be a generation-recombination center.

Optical properties of a series of CdTe/CdMnTe multi quantum weJl structures grown with MBE and ALE (CdTe quantum wells only) methods are compared. Based on the results of the photoluminescence experiments we conclude that the ALE growth leads to a different lateral scale of quantum welI width fluctuations, which results in different exciton properties in two multi quantum well systems studied. In the wells grown with ALE method excitons are less localized. They can migrate in a quantum well plane between quantum well regions varying in thickness by 1 monolayer. PACS numbers: 71.35.+z, 78.47.+p , 78.55.Et

We report on a study of photoluminescence from CdTe quantum wells (QW) surrounded by Cd 1 − x Mn x Te barriers. Previous investigations of this QW system were limited to the Mn molar fraction x in the barriers not exceeding x ≈ 0.3. Here, the study includes samples in the entire range of the molar fraction 0.1 x ≤ 1. The width of the investigated quantum wells ranged from 4 ML (~13 A) to 30 ML (~ 100 A). We report also on the temperature dependence of the PL line position. The luminescence persists up to room temperature evidencing a good quality of the samples even in the case of very deep QW, i.e. for wells and barriers differing significantly in their lattice parameters. Finally, we compare the observed PL energies from quantum wells with different x with calculations based on the envelope function method assuming a square-well potential. The excitonic effect and the effect related to internal strains are taken into account. The scatter of the data does not exceed that expected for QW width fluctuation and/or interface Mn interdiffusion by ± 1 ML.

The aim of our work was to produce p-n heterojunction with the high level of optical transmission. P-type NiO and n-type ZnO:Al films deposited by magnetron sputtering were used to fabricate p-n diodes. These were thermally processed in Ar ambient at 400°C in order to obtain high optical transmission and better electrical characteristics. The best diode's parameters were rectifying ratio of 6.7·104 and reverse current at the level of 6·10−7A at −3 V of bias. The best obtained optical transmission of the bilayer was near 20% in the visual wavelength region.

Generation of thermal donor centres in oxygen-rich silicon doped with boron and aluminium acceptors has been studied with the FTIR technique. It has been found that upon annealing 470°C two kinds of absorption series were generated. One of them belonged to the well-known first ionization 1eve1 of silicon thermal (double) donors (TD,s): TD° /TD+ . The second series was identified with the so-called shallow thermal donors (STD,s). The generation kinetics of the two series was followed for both kinds of acceptor doping and significant differences has been found. The results of the FTIR investigations were further compared with the magnetic resonance findings allowing for their mutual correlation and more general conclusions.

We report on the growth by molecular beam epitaxy of II‐VI semiconductor parabolic quantum wells. Cd1−xMnxTe diluted magnetic semiconductor was chosen for constructing these structures because of its extreme sensitivity to the presence of a magnetic field. Photoluminescence excitation spectra revealed several series of energetically equidistant peaks due to interband optical transitions. The energy separation in a given series scales proportionally to the inverse width of the quantum well as expected for a parabolic confining potential. Analysis of the spectra made possible a model‐independent determination of the valence band offset in CdTe/Cd1−xMnxTe.

We report successful growth of thin films of ZnO by atomic layer epitaxy (ALE). Properties of the ZnO films grown by ALE on GaN/sapphire are described in relation to those grown by the same sequential procedure on uncoated sapphire and glass substrates. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Despite many efforts the origin of a ferromagnetic (FM) response in ZnMnO and ZnCoO is still not clear. Magnetic investigations of our samples, not discussed here, show that the room temperature FM response is observed only in alloys with a non-uniform Mn or Co distribution. Thus, the control of their distribution is crucial for explanation of contradicted magnetic properties of ZnCoO and ZnMnO reported till now. In the present review we discuss advantages of the Atomic Layer Deposition (ALD) growth method, which enables us to control uniformity of ZnMnO and ZnCoO alloys. Properties of ZnO, ZnMnO and ZnCoO films grown by the ALD are discussed., Comment: 41 pages, 19 figures, 48 references, review paper

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In the hop conduction range, the dependence of the transverse magnetoresistance rho / rho 0 on the orientation and the magnitude of the magnetic induction beta (of several tesla) was studied in Ga-doped Ge samples with acceptor concentrations, NA, ranging from approximately=1-6*1015cm-3.

The AREDCs corresponding to the total density of states in the valence band of Cd 1-x Mn x Se crystals ( x = 0;0.4) were measured for surfaces of the crystals etched by the Ar ions and annealed. A comparison of the curves obtained for the two crystals shows the contribution of Mn 3 d electrons to the valence band of Cd 0.6 Mn 0.4 Se crystal. This contribution leads to an increase of the width of the first peak of the valence band ( p - d interaction) and to an appearance of an additional peak at 3.35 eV below the valence band edge. The AREDCs obtained for the two crystals are compared with the calculated total density of states distribution in the valence band [13]. Annealing of Cd 0.6 Mn 0.4 Se crystal in UHV leads to an appearance of the structure of the upper part of the valence band.