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Study of the nanometer crystalline silicon films
Abstracts
film and on the change of structure of deposited metallic films due to a decrease of the vacuum arc discharge current are also represented in the report. Structural schemes of the metallic plasma source and vacuum deposition 'Smena' machine as well as their technical characteristics are also represented.
about 495°C. P-E hysteresis curves were also observed in films obtained on Si at 5500600°C. The films obtained showed good step coverage characteristics.
Diamond films synthesized by microwave plasma CVD Study of the nanometer crystalline silicon films
Zhang Zhiming, Hong Ailing, Zhuang Zhichen, Zhu Pingfang and Wan Chen, ShanghaiJiaotong University, Shanghai 200030, China
He Yuliang, Physics Department, Nanjing University, Nanjing
210008, China In this paper, a report is made of a novel material named 'nanometer crystalline silicon films' (nc-Si: H), in which there is a structure made by fine-micro-crystallinities of silicon (6-8 nm). These films are produced by a conventional PECVD deposition system and the deposition parameters are carefully controlled. So, there is a strange structure difference both with a-Si:H and c-Si materials. The primary measurement shows that the room conductivity of nc-Si:H films is 4.7 x 10 -3 f~-l cm-~, this value is equal to the intrinsic c-Si. However, the activation energy of nc-Si:H is extremely small (0.1 ___0.03 eV) in the temperature range of 2000 ,';40 K, which shows that a transport mechanism of nc-Si:H differs from semiconductors conduction. We found out that in the PECVD deposition system under the control of technological parameters, can vary the morphology of growing films and promote the conductivity of films varying from 10-~0 to 10-2 D cm ~ without doping. It has an important significance for the application of studies of the related silicon devices. We also show the structure stability of nc-Si:H films is better than that of a-Si:H and #c-Si:H films. The famous S-W effect does not exist in nc-Si: H films.
Growth of PbTiO3 films by photo-MOCVD Masaru Shimizu, Takuma Katayama and Tadashi Shiosaki,
Department of Electronics, Faculty of Engineering, Kyoto University, Yoshida Honmaehi, Sakyo-ku, Kyoto 605, Japan Using photo-MOCVD, PbTiO3 thin films have been successfully grown on sapphire(0001), (0112) and (1120), MgO(100) and Si(100) at substrate temperatures of 4000700°C. Tetraethyl lead [Pb(C2Hs)4], titanium tetraisopropoxide [Ti(i-OC3H7)4] and oxygen were used as source materials. The light source used was a Xe-Hg lamp. The effects of growth parameters and uv light ixradiation on the growth of PbTiO3 were investigated. The observed effects of photo irradiation included the changes in crystalline quality, growth rate, surface morphology and electrical properties. PbTiO3 films with a perovskite structure were .grown at substrate temperatures higher than 600°C. Only when :films were obtained by photo-MOCVD, highly (111) oriented PbTiO 3were grown on sapphire(0001) at a substrate temperature ,of 600°C. PbTiO3 films obtained on MgO and Si had poly,crystalline structures. The growth rates of PbTiO3 films grown by photo-MOCVD were 25-180 A m i n - ~which are higher than those of the conventional sputtering methods. The photodeposited PbTiO3 films had dielectric constants of 300290 and loss tangents of 0.03~).19. The dielectric transition temperature measured in temperature dependence of dielectric constant was
The technique of diamond films synthesized by chemical vapor deposition has been rapidly developed in the past ten years. In this paper, the thin diamond films were fabricated by the microwave plasma CVD from the feed gases of acetone and hydrogen. The results were compared with those of thermal filament CVD which had been done before. The microwave frequency used in our experiments was 2.45 GHz and the reaction chamber was a 35 mm inner diameter quartz tube. The substrate was placed on the discharge area. The typical growth conditions are pressure between 5-50 torr, total gas flow rate of 100 sccm, acetone concentration between 0.4-2 vol% and microwave power of about 300 W. During the reaction, the silicon substrate was stricken by various active particles and its temperature could be as high as 900o1200 K. The deposits were examined by scanning electron microscopy, X-ray diffraction, Raman spectroscopy and Auger electron spectroscopy to determine their structures and qualities. Our research has shown that the fine diamond films could be obtained under certain conditions if the silicon substrate has been scratched by diamond powder suspended in ethyl alcohol where ultrasonic waves were passing. That was similar to thermal filament CVD. Moreover, the effects of acetone concentration and substrate temperature were similar for both methods and there existed optimal conditions respectively. But, different from the thermal filament CVD, the microwave plasma CVD was greatly affected by the variation of pressure. Under the higher pressure (30-40 torr), the substrate could not be sputtered since the free travel of the individual particle was short and its energy was not very high. That was favourable to the nucleation and growth of diamond and resulted in the perfect crystal structures. However, too high pressure would make the discharge unstable. In addition, the substrate position also had an influence on the deposition of diamond.
GaN single crystal films on silicon substrates grown by MOVPE Takao Nagatomo, Ichiro Ochiai, Shigeo Ookoshi and Osamu Omoto, Department of Electronics, Shibaura Institute of Tech-
nology, 9-14 3-chome, Shibaura, Minato-ku, Tokyo 108, Japan Wide bandgap semiconducting GaN has been widely investigated as a promising material for the blue light-emitting diodes (LEDs). Single crystal GaN films have been grown on (111) silicon substrates by MOVPE in an ambient hydrogen gas at atmospheric pressure. When the growth conditions of the V/Ill ratio of 700, growth rate of about 4 pm h - ~ and growth temperatures from 850 to 940°C were maintained, good-quality single crystal films were obtained. The properties of the films have been studied by the RHEED (reflection high-energy electron diffraction) technique, X-ray diffraction, electrical and optical measurements, and photoluminescence. 1069
film and on the change of structure of deposited metallic films due to a decrease of the vacuum arc discharge current are also represented in the report. Structural schemes of the metallic plasma source and vacuum deposition 'Smena' machine as well as their technical characteristics are also represented.
about 495°C. P-E hysteresis curves were also observed in films obtained on Si at 5500600°C. The films obtained showed good step coverage characteristics.
Diamond films synthesized by microwave plasma CVD Study of the nanometer crystalline silicon films
Zhang Zhiming, Hong Ailing, Zhuang Zhichen, Zhu Pingfang and Wan Chen, ShanghaiJiaotong University, Shanghai 200030, China
He Yuliang, Physics Department, Nanjing University, Nanjing
210008, China In this paper, a report is made of a novel material named 'nanometer crystalline silicon films' (nc-Si: H), in which there is a structure made by fine-micro-crystallinities of silicon (6-8 nm). These films are produced by a conventional PECVD deposition system and the deposition parameters are carefully controlled. So, there is a strange structure difference both with a-Si:H and c-Si materials. The primary measurement shows that the room conductivity of nc-Si:H films is 4.7 x 10 -3 f~-l cm-~, this value is equal to the intrinsic c-Si. However, the activation energy of nc-Si:H is extremely small (0.1 ___0.03 eV) in the temperature range of 2000 ,';40 K, which shows that a transport mechanism of nc-Si:H differs from semiconductors conduction. We found out that in the PECVD deposition system under the control of technological parameters, can vary the morphology of growing films and promote the conductivity of films varying from 10-~0 to 10-2 D cm ~ without doping. It has an important significance for the application of studies of the related silicon devices. We also show the structure stability of nc-Si:H films is better than that of a-Si:H and #c-Si:H films. The famous S-W effect does not exist in nc-Si: H films.
Growth of PbTiO3 films by photo-MOCVD Masaru Shimizu, Takuma Katayama and Tadashi Shiosaki,
Department of Electronics, Faculty of Engineering, Kyoto University, Yoshida Honmaehi, Sakyo-ku, Kyoto 605, Japan Using photo-MOCVD, PbTiO3 thin films have been successfully grown on sapphire(0001), (0112) and (1120), MgO(100) and Si(100) at substrate temperatures of 4000700°C. Tetraethyl lead [Pb(C2Hs)4], titanium tetraisopropoxide [Ti(i-OC3H7)4] and oxygen were used as source materials. The light source used was a Xe-Hg lamp. The effects of growth parameters and uv light ixradiation on the growth of PbTiO3 were investigated. The observed effects of photo irradiation included the changes in crystalline quality, growth rate, surface morphology and electrical properties. PbTiO3 films with a perovskite structure were .grown at substrate temperatures higher than 600°C. Only when :films were obtained by photo-MOCVD, highly (111) oriented PbTiO 3were grown on sapphire(0001) at a substrate temperature ,of 600°C. PbTiO3 films obtained on MgO and Si had poly,crystalline structures. The growth rates of PbTiO3 films grown by photo-MOCVD were 25-180 A m i n - ~which are higher than those of the conventional sputtering methods. The photodeposited PbTiO3 films had dielectric constants of 300290 and loss tangents of 0.03~).19. The dielectric transition temperature measured in temperature dependence of dielectric constant was
The technique of diamond films synthesized by chemical vapor deposition has been rapidly developed in the past ten years. In this paper, the thin diamond films were fabricated by the microwave plasma CVD from the feed gases of acetone and hydrogen. The results were compared with those of thermal filament CVD which had been done before. The microwave frequency used in our experiments was 2.45 GHz and the reaction chamber was a 35 mm inner diameter quartz tube. The substrate was placed on the discharge area. The typical growth conditions are pressure between 5-50 torr, total gas flow rate of 100 sccm, acetone concentration between 0.4-2 vol% and microwave power of about 300 W. During the reaction, the silicon substrate was stricken by various active particles and its temperature could be as high as 900o1200 K. The deposits were examined by scanning electron microscopy, X-ray diffraction, Raman spectroscopy and Auger electron spectroscopy to determine their structures and qualities. Our research has shown that the fine diamond films could be obtained under certain conditions if the silicon substrate has been scratched by diamond powder suspended in ethyl alcohol where ultrasonic waves were passing. That was similar to thermal filament CVD. Moreover, the effects of acetone concentration and substrate temperature were similar for both methods and there existed optimal conditions respectively. But, different from the thermal filament CVD, the microwave plasma CVD was greatly affected by the variation of pressure. Under the higher pressure (30-40 torr), the substrate could not be sputtered since the free travel of the individual particle was short and its energy was not very high. That was favourable to the nucleation and growth of diamond and resulted in the perfect crystal structures. However, too high pressure would make the discharge unstable. In addition, the substrate position also had an influence on the deposition of diamond.
GaN single crystal films on silicon substrates grown by MOVPE Takao Nagatomo, Ichiro Ochiai, Shigeo Ookoshi and Osamu Omoto, Department of Electronics, Shibaura Institute of Tech-
nology, 9-14 3-chome, Shibaura, Minato-ku, Tokyo 108, Japan Wide bandgap semiconducting GaN has been widely investigated as a promising material for the blue light-emitting diodes (LEDs). Single crystal GaN films have been grown on (111) silicon substrates by MOVPE in an ambient hydrogen gas at atmospheric pressure. When the growth conditions of the V/Ill ratio of 700, growth rate of about 4 pm h - ~ and growth temperatures from 850 to 940°C were maintained, good-quality single crystal films were obtained. The properties of the films have been studied by the RHEED (reflection high-energy electron diffraction) technique, X-ray diffraction, electrical and optical measurements, and photoluminescence. 1069