Effect Of Subsequent Thermal Annealing Research Articles

Improvement in the aged silicon solar cells parameters by thermal annealing

In this paper, to simulate and accelerate the effects of aging, solar cells were exposed to the different doses of co60 gamma radiation. The current–voltage (I–V) characteristics of mono-crystalline solar cells under AM1.5 illumination condition were studied before and after the gamma irradiation. Experimental results showed that the solar cell parameters such as open circuit voltage (Voc), short circuit current (Isc) and efficiency (η) decrease with the increase of the gamma radiation doses. The effect of subsequent thermal annealing on solar cells degraded by gamma irradiation is investigated. A significant improvement in the electric parameters of by low doses gamma irradiated silicon solar cells is observed after the thermal annealing.

Annealing temperature dependent photoluminescence and afterglow of undoped CaAl2O4

Undoped CaAl2O4 nanocrystals were synthesized via sol–gel combustion technique, and the effects of subsequent thermal annealing on the photoluminescence (PL) and afterglow of undoped CaAl2O4 nanocrystals were investigated by means of X–ray diffractometry, PL spectroscopy and afterglow dosimetry, respectively. As the annealing temperature increases from 200 to 750 °C, the PL spectrum of undoped CaAl2O4 consists of one blue PL subband and one violet PL subband with their peak energies varying in the range of 2.67–2.86 eV and 3.12–3.31 eV, respectively. It is found that annealing CaAl2O4 can generate significant impacts on the PL and afterglow properties of undoped CaAl2O4. On one hand, the integrated PL intensity of undoped CaAl2O4 decreases with the annealing temperature. On the other hand, the blue afterglow intensity of undoped CaAl2O4 varies with the annealing temperature. More importantly, the duration of the blue afterglow can be extended seven times from 1.98 to 14.25 s when CaAl2O4 is annealed at 600 °C for 2 h. On the basis of density functional calculations, our work demonstrates that oxygen vacancies in CaAl2O4 are the luminescence center of the blue afterglow. In addition to providing valuable insight toward rational development of more efficient afterglow materials, these results are helpful for promoting our fundamental understanding of the afterglow mechanisms of Eu2+ doped CaAl2O4.

Characteristics of SiOx-cored composite nanowires with Pd shell layers

This paper describes the fabrication of Pd-coated SiOx nanowires via a simple approach and reports the effects of subsequent thermal annealing. While the as-synthesized Pd-coated SiOx nanowires exhibited smooth one-dimensional (1D) nanostructures, the thermal annealing induced a rough surface. X-ray diffraction, selected area electron diffraction, and lattice-resolved transmission electron microscopy coincidentally revealed that the assynthesized Pd-coated SiOx nanowires were comprised of a cubic Pd phase, whereas annealing generated a tetragonal PdO phase. Micro-Raman spectroscopy measurements showed the presence of 630 cm−1-peak, which can be assigned to the B1g mode of single crystal PdO, whether samples had been annealed or not. Although both Pd and PdO phases did not exhibit PL emission, the PL intensity of core SiOx nanowires has been significantly reduced by the Pd-coating, presumably due to the covering effect.

Thin film silicon solar cells for space applications: Study of proton irradiation and thermal annealing effects on the characteristics of solar cells and individual layers

The paper reports on the effects of a proton irradiation campaign on a series of thin-film silicon solar cells (single- and double-junction). The effect of subsequent thermal annealing on solar cells degraded by proton irradiation is investigated. A low-temperature annealing behaviour can be observed (at temperatures around 100 to 160°C) for microcrystalline silicon solar cells. To further explore this effect, a second proton irradiation campaign has been carried out, but this time on microcrystalline silicon layers. The effect of proton irradiation and subsequent thermal annealing on the optical and electronic properties of microcrystalline silicon is, thus, thoroughly investigated.

E′ and B 2 center production in amorphous quartz by MeV Si and Au ion implantation

Amorphous SiO 2 was implanted with Si + and Au 2+ ions at energies of 4 and 3 MeV, respectively. The doses ranged from 0.3×10 17 to 1.5×10 17 ions cm −2, and a current density of 30 μA cm −2 was used. The formation of E′ and B 2 centers was observed for both ions by optical absorption and electron paramagnetic resonance (for E′ defects) measurements. For Si implantation, there is a saturation of E′-center formation for doses higher than 1.0×10 17 Si cm −2; Au implantation produces E′-center annealing for sufficiently high doses. The heating effect due to the relatively high current density induces spontaneous formation of Au nanoparticles already during the ion bombardment. The effect of subsequent thermal annealing in a reducing atmosphere at 600 and 900°C on the E′ and B 2 centers was also studied.

High energy high dose Si implantation into Ge and the effect of subsequent thermal annealing

A mirror polished (111)-oriented Ge single crystal substrate was implanted with 1.0 MeV Si+ ions to a dose of ∼ 8.5 × 1017 cm−2 at room temperature. Rutherford backscattering spectrometry (RBS) together with ion channeling analysis with H+ and He+ beams have been used to study the Si distribution and radiation damage after implantation and subsequent vacuum annealing in the temperature range of 500–850°C. A non-RBS (resonance) measurement with an H+ beam of specified energy is used to study the Si atoms distribution in Ge. The experiments reveal the existence of an extensive damage (possibly an amorphous layer) buried at a depth corresponding to the peak Si concentration. Annealing up to 850°C for 30 min does not result in the complete recovery of the lattice order. The annealing temperature dependence of the damage depth distributions in Ge has been evaluated using the multiple scattering model of Feldman and Rodgers. The composition of the alloy layer was measured by RBS followed by computer-simulated spectrum analyses. A tentative explantation of the results is presented.

Characterization of phase transformation in titanium polycide films

Silicide formation on polysilicon from deposited titanium films and effects of subsequent thermal annealing at different temperatures (C-C) have been investigated by grazing-angle XRD, AFM, ESCA and sheet resistance measurements. The results indicated formation of a high-resistivity isomorphic phase (C49), polymorphic phases (C49 and C54) and low-resistivity isomorphic C54 films at low, medium and high annealing temperatures from C to C. The complete conversion from C49 to isomorphic C54 phase occurs at about C. The influence of phase formations and polymorphic transformation on the surface morphology is studied by estimating the r.m.s. surface roughness using AFM. Samples annealed at C have the highest surface roughness of 15.47 nm owing to agglomeration of C54 grains in films. XPS studies showed the formation of a thin layer of on the surface of .

Elevated temperature Ge implantation into Si and the effect of subsequent thermal annealing

The effect of implantation temperature and subsequent thermal annealing on the defect structure and strain state of Ge implanted Si is examined. It is shown that ion-beam synthesised SiGe Si strained layer heterostructures are most effectively fabricated by implanting at low temperatures, to form a thick amorphous layer, followed by solid-phase epitaxial crystallisation. In cases where extended defects are produced during implantation, high temperature (∼ 1050°C) annealing is shown to improve the quality of the material by substantially reducing the dislocation density. However, the annealed layers are shown to contain high dislocation densities, ∼ 2 × 10 8 cm −2, and significant Ge diffusion is observed. The dislocations are shown not to cause significant strain relief in the SiGe alloy layers but may be problematic in certain device applications.

Effects of HF cleaning and subsequent heating on the electrical properties of silicon (100) surfaces

Changes in surface-band bending of both boron-doped and phosphorus-doped silicon (100) samples by exposure (40 s) to hydrofluoric acid (HF) with varying HF concentrations were studied by x-ray photoelectron spectroscopy. Effects of subsequent thermal annealing was investigated by in situ heating in vacuum. Hydrogen termination of the dangling bonds on silicon was found to be an effective means to reduce surface gap states on silicon. Near-flatband surfaces were observed on both n- and p-Si by the HF exposure when the doping concentration was not less than 1×1016/cm3, and when the HF concentration was not higher than 5%. A higher HF concentration promoted hydrogen diffusion and the formation of an H-B species in p-Si. As such, band bending increased on p-Si. However, the deactivation of boron could be recovered by annealing for less than 1 h at a temperature as low a 120 °C.