In this paper, contactless transient photo-conductance measurements are applied to p-doped mono-crystalline Silicon (p-Si) coated by two different kinds of aluminum oxide (Al<sub>2</sub>O<sub>3</s...In this paper, contactless transient photo-conductance measurements are applied to p-doped mono-crystalline Silicon (p-Si) coated by two different kinds of aluminum oxide (Al<sub>2</sub>O<sub>3</sub>) layers in order to study alternative routes to the standard atomic layer deposition (ALD). The aluminum oxides layers were deposited by either spin coating or ion layer gas reaction (ILGAR?). For both coatings an increase of the charge carrier life time is observed indicating a passivation of the p-Si surface. This study shows alternative deposition methods and the potential of transient photocon- ductance measurements for the elucidation of the origin of the passivation. We show that the passivation induced by coating deposited via ILGAR is at least partially due to charge carrier trapping and storage at the interface. It was also surprisingly found that for those coatings, annealing at 425℃ leads to a decrease of the life time. This points to temperature instability for both coatings.展开更多
As an organic photoconductor, the photosensitivity of x-copper phthalocyanine （x-PcCu）is quite a good one among a variety of polymorphic forms of PcCu. Basing on our previous studies on evaporated films of α-PcCu, ...As an organic photoconductor, the photosensitivity of x-copper phthalocyanine （x-PcCu）is quite a good one among a variety of polymorphic forms of PcCu. Basing on our previous studies on evaporated films of α-PcCu, we prepared sandwich cells—Ag（-）/x-PcCu/SnO<sub>2</sub>（+） with x-PcCu prepared at low vacuum and high evaporation rate. These sandwich cells showed a high ratio of photo-to dark-conductivity. Under an irradiation of 17.7 mW/cm<sup>2</sup> from a tungsten lamp and an electrical field of 2×10<sup>5</sup>展开更多
A series of Si-rich amorphous silicon carbide （a-SiC：H） thin films were deposited in conventional plasma enhanced chemical vapor deposition system with various gas ratio R = [CH4]/[SiH4]. The microstructural, optic...A series of Si-rich amorphous silicon carbide （a-SiC：H） thin films were deposited in conventional plasma enhanced chemical vapor deposition system with various gas ratio R = [CH4]/[SiH4]. The microstructural, optical and electronic properties of as-deposited films were investigated in this study. It was found that optical band gap was linearly proportional to carbon content in the films and it could be controlled in a range of 1.8-2.4 eV by changing the gas ratio, R. Both dark and photo conductivities in room temperature were decreased with the increasing of carbon content in the films, and the photosensitivity reached as high as 104 for the film with the optical band gap of 1.96 eV. The as-deposited samples were subsequently annealed at the temperatures of 900℃ and 1000℃. The formation of nanocrystalline silicon （nc- Si） dots in amorphous silicon carbide （a-SiC） host matrix was shown. The dark conductivity was enhanced by five orders of magnitude after annealing compared with that of as-deposited films. The result of temperature-dependent conductivity suggested that the property of carrier transport was dominated by conduction process between the extended states. Furthermore, room temperature electroluminescence （EL） was achieved from nc-Si/SiC system and the possible mechanism of radiative recombination mechanism was discussed.展开更多
文摘In this paper, contactless transient photo-conductance measurements are applied to p-doped mono-crystalline Silicon (p-Si) coated by two different kinds of aluminum oxide (Al<sub>2</sub>O<sub>3</sub>) layers in order to study alternative routes to the standard atomic layer deposition (ALD). The aluminum oxides layers were deposited by either spin coating or ion layer gas reaction (ILGAR?). For both coatings an increase of the charge carrier life time is observed indicating a passivation of the p-Si surface. This study shows alternative deposition methods and the potential of transient photocon- ductance measurements for the elucidation of the origin of the passivation. We show that the passivation induced by coating deposited via ILGAR is at least partially due to charge carrier trapping and storage at the interface. It was also surprisingly found that for those coatings, annealing at 425℃ leads to a decrease of the life time. This points to temperature instability for both coatings.
文摘As an organic photoconductor, the photosensitivity of x-copper phthalocyanine （x-PcCu）is quite a good one among a variety of polymorphic forms of PcCu. Basing on our previous studies on evaporated films of α-PcCu, we prepared sandwich cells—Ag（-）/x-PcCu/SnO<sub>2</sub>（+） with x-PcCu prepared at low vacuum and high evaporation rate. These sandwich cells showed a high ratio of photo-to dark-conductivity. Under an irradiation of 17.7 mW/cm<sup>2</sup> from a tungsten lamp and an electrical field of 2×10<sup>5</sup>
基金Acknowledgements This work was supported by National Natural Science Foundation of China （Grant No. 61036001）, the National Science Foundation of Jiangsu province （No. BK2010010） and the Fundamental Research Funds for the Central Universities （No. 1112021001）.
文摘A series of Si-rich amorphous silicon carbide （a-SiC：H） thin films were deposited in conventional plasma enhanced chemical vapor deposition system with various gas ratio R = [CH4]/[SiH4]. The microstructural, optical and electronic properties of as-deposited films were investigated in this study. It was found that optical band gap was linearly proportional to carbon content in the films and it could be controlled in a range of 1.8-2.4 eV by changing the gas ratio, R. Both dark and photo conductivities in room temperature were decreased with the increasing of carbon content in the films, and the photosensitivity reached as high as 104 for the film with the optical band gap of 1.96 eV. The as-deposited samples were subsequently annealed at the temperatures of 900℃ and 1000℃. The formation of nanocrystalline silicon （nc- Si） dots in amorphous silicon carbide （a-SiC） host matrix was shown. The dark conductivity was enhanced by five orders of magnitude after annealing compared with that of as-deposited films. The result of temperature-dependent conductivity suggested that the property of carrier transport was dominated by conduction process between the extended states. Furthermore, room temperature electroluminescence （EL） was achieved from nc-Si/SiC system and the possible mechanism of radiative recombination mechanism was discussed.
