Photoluminescent properties of Al₂O₃ films containing gold nanoparticles, which are prepared by pulse laser deposition

Photoluminescent porous films of aluminum oxide containing gold nanoparticles were prepared using pulse laser deposition from backward flow of particles from erosion torch. Measurements of time-resolved photoluminescence spectra revealed high intense photoluminescent band with the peak close to 2.4 eV and its low-energy shoulder at 1.6 - 1.7 eV, high-energy shoulder at 2.9 eV, with relaxation times up to several microseconds. Studied were the influence of formation conditions and gold concentrations in the target on photoluminescent properties of films. The nature of photoluminescence related with radiative recombination of electrons and holes in Au nanoparticles as well as local centers in Al₂O₃ matrix is discussed

Zn and Mn impurity effect on electron and luminescent properties of porous silicon

Investigated in this work are por-Si/n-Si structures prepared by anodizing silicon in 1 % HF water solution, which was followed by natural aging in air and doping with Zn and Mn impurities. When aging, the oxide film of nanoelements in the above structures is substituted by a silicate one. Measurements of temperature dependencies (100...300 K) describing the capacitance photovoltage behavior caused by intense pulses (∼10²¹ quanta/cm2s) of red or white light enabled us to determine the following values and their changes: the boundary potential for n-Si, distribution of the concentration inherent to boundary electron states in the n-Si forbidden gap, concentration of traps for non-equilibrium holes at the interface por-Si/n-Si and in the por-Si layer. The substitution of the oxide film by the silicate one, the thickness of which can exceed the initial thickness of the oxide film, makes these structures more stable and results in sizable changes of spectral dependencies of the short-time (t < 250 ns) and integrated (t > 250 ns) photoluminescence relaxation components as well as shifts the latter into the shortwave range

Effect of microwave electromagnetic radiation on the structure, photoluminescence and electronic properties of nanocrystalline silicon films on silicon substrate

We studied the effect of microwave electromagnetic radiation on silicon low-dimensional structures. The nanocrystalline silicon (nc-Si) films on p-Si substrate were formed with pulsed laser ablation. The surface morphology of films was studied with atomic force microscopy. We made X-ray phase analysis of films and measured strains in the structures obtained using X-ray diffractometry. We also investigated the time-resolved photoluminescence (PL) spectra and temperature dependence of photovoltage for the nc-Si/p-Si and nc- Si/p-Si structures, both before and after exposure to magnetron microwave radiation of moderate (1.5 W/cm²) irradiance. It was shown that after microwave irradiation photovoltage in the nc-Si films, as well as electron trap concentration in both the films and p-Si substrates, decrease. After irradiation of the nc-Si/p-Si structures the density of interfacial electron states (IES) decreases, while both PL intensity and relaxation time increase. At the same time irradiation of the nc-Si/p-Si structures that had high values of PL intensities and relaxation times before irradiation results in decrease of these values, as well as somewhat increases the density of IES. Higher (7.5 W/cm2) irradiance of microwave field impairs the PL properties (to the point of complete disappearance of PL). In addition it induces changes in film structure resulting, in the course of time, in decrease of strains in the structures studied. We discuss some mechanisms for microwave field effect on the properties of these structures

Zn and Mn impurity effect on electron and luminescent properties of porous silicon

Investigated in this work are por-Si/n-Si structures prepared by anodizing silicon in 1 % HF water solution, which was followed by natural aging in air and doping with Zn and Mn impurities. When aging, the oxide film of nanoelements in the above structures is substituted by a silicate one. Measurements of temperature dependencies (100...300 K) describing the capacitance photovoltage behavior caused by intense pulses (∼10²¹ quanta/cm2s) of red or white light enabled us to determine the following values and their changes: the boundary potential for n-Si, distribution of the concentration inherent to boundary electron states in the n-Si forbidden gap, concentration of traps for non-equilibrium holes at the interface por-Si/n-Si and in the por-Si layer. The substitution of the oxide film by the silicate one, the thickness of which can exceed the initial thickness of the oxide film, makes these structures more stable and results in sizable changes of spectral dependencies of the short-time (t 250 ns) photoluminescence relaxation components as well as shifts the latter into the shortwave range