As Si is an indirect band gap material, the PL generated by phonon assisted band-to-band (B2B) radiative recombination (of energy equal to energy gap of Si) is very weak; about 10 orders of magnitude lower than the exciting photon flux [1] . If crystallographic defects are present then at room temperature an additional broad defect PL peak is generated (DPL) with energy smaller than the band gap of Si [1] , [2] , [3] . At room temperature, defect-band PL intensity is orders of magnitude lower than the B2B intensity [1] .

In this work, molybdenum and tungsten-implanted wafers are analyzed by an innovative technique based upon photoluminescence measurements, with the aim to assess the ability of this technique to detect metal contamination in the near-surface region. Surface Photovoltage (SPV) measurements of carrier diffusion length are compared to the results of photoluminescence measurements. It is shown that molybdenum and tungsten contamination are easily detected by photoluminescence intensity measurements down to about 10 10 cm − 2 contaminant dose. Vice versa, SPV has limited sensitivity to these elements ( ≥ 5 · 10 10 cm − 2 ), because of their low diffusivity. Therefore, photoluminescence intensity measurement can be a valid alternative to conventional carrier diffusion length measurements for monitoring slow diffuser contamination.

The optical properties of p-type, n-type and nominally undoped (AlxGa1−x)yIn1−yP layers have been determined in a wide spectral range. The layers under study have been chosen with compositions and dopant concentrations which make them interesting for their use in III-V multijunction solar cells. The layers have been measured by variable angle spectroscopic ellipsometry and, irrespective of composition and doping, their optical response has been modelled using the same model dielectric function consisting of two asymmetric Tauc-Lorentz oscillators and a 3D-M0 Adachi term. The results show that transition energy values change with layer composition, whilst for layers of the same material (i.e. GaInP or AlInP), the band-gap transition energy E0 shows a strong dependence on the order parameter. The refractive indexes and extinction coefficients deduced from the ellipsometric data have been used to fit reflectance measurements for the same layers and an excellent agreement has been achieved, thus validating the model dielectric function proposed for this kind of materials.

The advantages of surface pattern and mesoporous character of silica thin films were combined, while preserving the interconnected pore system or creating laterally separated porous volumes surrounded by nonpermeable compact zones.

This study reveals the connection between the silver-doping method, the resulting nature and amount of the silver dopant together with the structural properties and the long-term antibacterial activity of composite coatings.

Charge injection and retention behaviors of metal-nitride-oxide-silicon (MNOS) memory structures with Si or Ge nanocrystals embedded at a depth of 3nm in the nitride layer were studied. The effect of Si nanocrystals on these properties was opposite in comparison with that of Ge nanocrystals. To understand the origin of these opposite effects, the influence of the oxide thickness and of the depth, size and location of semiconductor nanocrystals has been studied on the charging behavior of MNOS non-volatile memory structures by the calculation of electron and hole tunneling probabilities, and by the simulation of memory window, memory hysteresis and retention behavior.

A CIGS PV szerkezet kutatasanak celja az egyutt-parologtatasos előallitasnal fellepő folyamatok megismerese; es az n-tipusu puffer-reteg letrehozasa vakuumtechnikailag zart ciklusba rendezhető modon. Utobbit az atomi reteg-levalasztasi technika hazai bevezetesevel oldottuk meg. Kb. 200 ciklusban Zn-es 2 at% Al prekurzor-technikaval Al-mal adalekolt ZnO-retegek uveg hordozon T= 210-220°C-on reprodukalhatoan kialakithatok n=1,2•1021cm-3 adalekkoncentracioval, µ= 0.7 cm2/Vs mozgekonysaggal ill. ρ≈2 mΩcm (1 ill. 7 mΩcm lateralis es normalis) vezetőkepesseggel. A CIGS retegnovesztest un. flash-parologtatasos modszerrel es utolagos szelenizacioval vizsgaltuk. Ampullaban, egyuttes parologtatassal (T=500°C, t=15min) csak kalkopirit osszetevők mutathatok ki, a hőkezeles csak a Ga-tartalmat befolyasolja. Az idealis CuIn0,8Ga0,2Se2 osszetetel 10-15 perces hőkezelessel beallithato a szokasos morfologiaval, amit konformalisan fed be a kb. 40nm ALD pufferreteg . Uvegen, Mo-elektrodra parologtatott (In, Ga) es porlasztott (Cu) femosszetevők retegsorrendjenek szerepe dontő utolagosan szelenizalt retegszerkezeten. Felparologtatott Se-forras hőkezelesevel (valtozo gőznyomason) vakuumban a szelenizacio nem sikeres, de konstans gőznyomason (ampullaban) tokeletes, ha a femretegek sorrendje In, Ga, Cu. | The research on CuInGaSe2 (CIGS) thin film PV structures aimed at understanding of fundamental phenomena at the co-evaporation of the absorber layer; and the development of n-type buffer-layer by an integrable vacuum-method. Latter problem was solved by the adoption of the Atomic Layer Deposition (ALD) technique. In ca. 200 cycles of alternating Zn and ca. 2at% Al precursor pulses Al-doped ZnO layers on glass substrates could be formed reliably at T= 210-220°C with n=1,2•1021cm-3 doping concentration, µ= 0.7 cm2/Vs mobility and ρ≈2 mΩcm (1 vs. 7 mΩcm lateral and normal) resistivity. CIGS layer growth by the "flash-evaporation" method and with the post-selenisation of the metallic precursors was studied. Co-evaporation at T=500°C, t=15min results in solely chalcopyrite components, annealing time affects only the Ga-content in the layer. The composition CuIn0,8Ga0,2Se2 ideal for PV application can be set by an annealing for 10-15 min with the usual morphology, to be covered conformally by the ca. 40nm ALD buffer. The influence of the sequence of evaporated (In, Ga) and sputtered (Cu) metallic components on Mo-coated glass was studied by structural analyses on post-selenized d= 800…1200 nm layers. By the annealing of evaporated Se-source on top in vacuum (i.e. at varying Se vapour pressure) selenization was not successful. At constant vapour pressure (ampoule method) with a metal-layer order of In, Ga, Cu selenization is perfect.

The charging behavior of MNS (metal-nitride-silicon) and MNOS (metal-nitride-oxide-silicon) structures containing Si or Ge nanocrystals were studied by capacitance-voltage (C-V) and memory window measurements and by simulation. Both the width of hysteresis of C-V characteristics and the injected charge exhibited exponential dependence on the charging voltage at moderate voltage values, while at high voltages the width of hysteresis of C-V characteristics and the injected charge exhibited saturation. The memory window for reference MNS structure without nanocrystals was wider than that for reference MNOS structures. The presence of nanocrystals enhanced the charging behavior of MNOS structures, but in MNS structures nanocrystals exhibited the opposite effect. The main conclusion is that the presence of nanocrystals or other deep levels close to the Si surface enhances the charge injection properties due to the increased tunneling probability, but nanocrystals or other deep levels located far from the Si surface in the nitride layer do not enhance, but even can degrade the charging behavior by the capture of charge carriers. (C) 2012 Elsevier B. V. All rights reserved.

A thermopile structure is proposed for the detection of microwave/millimeter wave radiation. The thermopairs in the suggested linear arrangement function as antennas. 5.58 V/W responsivity was achieved at 100 GHz with 40 serial connected thermopairs. The experimentally observed polarity and frequency dependence convincingly verify the proper detector operation.

A novel MEMS thermopile structure is presented, in which the thermopairs act as dipole antennas. The induced current heats the hot point of the thermopairs. The thermoelectric output voltage is proportional to the absorbed radiation power. The antenna-like feature of the device is demonstrated by the dependence of the sensitivity on the polarization. 5.58 V/W responsivity was achieved at 0.1 THz without optimizing the structure and the measuring conditions.

Memory structures with an embedded sheet of separated Si or Ge nanocrystals were prepared by low pressure chemical vapour deposition using a Si3N4 control and SiO2 tunnel layers. It was obtained that a properly located layer of semiconductor nanocrystals can improve both the charging and retention behaviour of the MNOS structures simultaneously. Memory window width of above 6 V and retention time of 272 years was achieved for charging pulses of 15 V, 10 ms.

Memory structures with an embedded sheet of separated Si nanocrystals were prepared by low pressure chemical vapour deposition using a Si3N4 control layer and SiO2 or Si3N4 tunnel layers. It was obtained that a properly located layer of Si nanocrystals improves the charging behaviour of the MNOS structures. Memory window width of about 6.6 V and retention time of 41 years has been achieved for charging pulses of plusmn15 V, 10 ms.

The physical background and present status of the application of metal-insulator-silicon structures with semiconductor nanocrystals embedded in the insulator layer for memory purposes is breafly summarized.

Ge-rich SiO2 layers on top of Si substrates were deposited using plasma enhanced chemical vapour deposition. Ge nanocrystals embedded in the SiO2 layers were formed by high temperature annealing. The samples were measured and evaluated by spectroscopic ellipsometry. Effective medium theory (EMT) and parametric semiconductor models have been used to model the dielectric function of the layers. Systematic dependences of the layer thickness and the oscillator parameters have been found on the annealing temperature (nanocrystal size).

Ge nanocrystals were formed by electron beam evaporation on SiO2 covered Si substrates. The size and distribution of the nanocrystals were studied by atomic force microscopy, scanning electron microscopy and cross-sectional transmission electron microscopy. Dependencies of the nanocrystal size, of the nanocrystal surface coverage, and sheet resistance obtained by van der Pauw method of the Ge layer have been found on the evaporation time. The suggested growth mechanism for the formation of nanocrystals is the Volmer-Weber type. The sheet resistance exhibited a power dependence on the nanocrystal size.

Charging effects in CdSe nanocrystals embedded in SiO2 matrix fabricated by rf magnetron co-sputtering technique were electrically characterized by means of capacitance-voltage (C-V) combined with current-voltage (I-V). The presence of CdSe nanocrystals was demonstrated by X-ray diffraction technique. The average size of nanocrystals was found to be approximately 3nm. The carriers transport in the CdSe/SiO2 structure was shown to be a combination of Fowler-Nordheim tunnelling and Poole-Frenkel mechanisms. A memory effect was demonstrated and a retention time was measured.

CdSe nanocrystals (NCs) embedded in a solid SiO2 matrix were fabricated by RF-sputtering technique. Raman and photoluminescence spectroscopy illustrated the NCs size dependent confinement effect. The CdSe NCs charging effects were electrically characterized by means of capacitance–voltage measurements. A memory effect was demonstrated through memory window measurements.

SiO2 layer structures with a middle layer containing Ge nanocrystals were prepared by sputtering on n- and p-type Si substrates, and by consecutive annealing. Ge content in the middle layer was varied in the range of 40–100%. Most of the structures exhibited low breakdown voltages. The current through the structures became Schottky-like after breakdown. However, some p-type samples showed a considerable memory effect. It was obtained by spectroscopic ellipsometry that the middle layer contains amorphous Ge phase as well. The results also suggest intermixing of the layers during the sputtering and/or the annealing process.