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Study of behaviour of metal clusters on substrates with STM
Abstracts
and X R D measurements show that there are serious interdiffusion and interface reactions in samples annealed at temperatures higher than 650°C. The possible reaction products are Ba2SiO4 and Ba3SiOs. No new chemical compound related to copper was found. RBS measurements show that Cu ions diffused deeply into Si(100) substrate and play the role of a fast diffuser and Ba ions are concentrated in an area near the interface. The result of AES measurement is in agreement with that of RBS measurements. A thin layer of ZrO2 may slow down the interdiffusion process significantly.
structure. The infrared spectrum of AISt3 monolayers in the multilayer has been measured by Fourier transform infrared spectroscopy monolayers. The absorption intensity of CH2 stretching vibration vs AISt3 layer number is compared with optical multilayer calculation. The periodic structure of the hybrid multilayer is revealed by low angle X-ray diffraction. These show that the arrangement of A1St3 film deposited on a new solid surface of A1203 film is the same as that on the initial substrate surface. It is suggested that this method for building a L-B film/alumina multilayer structure could be applied to the study of nonlinear optical properties of Langmuir-Blodgett films.
The tantalum/aluminum alloy resistive film containing aluminum 50 at% Study of behaviour of metal clusters on substrates with STM Yang Bangchao and Jia Yuming, University of Electronic Science
and Technology of Chengdu, Chengdu 610054, China In this paper, both the tantalum/aluminum alloy resistive film containing aluminum 50 at% and the mid-power thin-film attenuator used for microwave circuits are studied and analyzed. The Ta/A1 alloy film containing A1 50 at% has high resistance stability. The alloy film is deposited by sputtering from a tantalum cathode which is covered partly by aluminum discs. The aluminum part of the target area is approximately 43% of the total. It is found that the alloy film could be used for a stable power resistor and its network. The main properties of the resistor as follows : atomic content Ta:A1 = 53.7:46.3; specific resistivity, 150-300 # ~ cm; temperature coefficient of resistance - 7 0 + 2 0 ppm '~C- ~; aged at 200°C for 96 h R/R < 0.3% ; and temperature circle ( - 1 0 to +200°C/5 times) R/R < 0.5%. The mid-power thin film attenuator used for microwave circuits is also described in this paper. This attenuator is made from the Ta/A1 alloy film containing aluminum 50 at%. The formula derived for attenuation and characteristic impedance of attenuator with n-tape network pattern will prove to be of benefit for the design of thin-film attenuators. The design of power or midpower thin-film attenuator has been discussed. Finally, the fabrication and assembly of the attenuator have been introduced. The indexes of the annenuator are : dimension 13.86 x 13.40 x 0.60 mm; power loading 25 W ; average power density 1.75 W mm 2; maximum power density 3.8 W m m - 2 ; attenuation 11.5 dB; characteristic impedance 50; frequency range 0-540 MHz ; and voltage standing-wave ratio < 1.08. The results above indicate that the mid-power thin-film attenuator has satisfied the demands of the user completely and it has not been previously reported in our country.
Study of CH2 stretching vibration in AISt3 L-B film/alumina hybrid multilayer by infrared spectroscopy
Wang Dongsheng, Ma Zili, Xue Zengquan and Wu Quande,
Department of Radio-Electronics, Peking University and Beo'ing Laboralory of Vacuum Physics, Academia Sinica, Beo'ing 100871, China Clusters are small particles whose size is less than l 0 3 /~. They possess special characteristics compared with the same bulk element material. Sometimes we find some clusters on the deposited thin films. These clusters will affect the structures and characteristics of the films, especially in semiconductor devices, where they will affect device quality. A scanning tunnelling microscope (STM) possesses atom level resolution for analysing sample surfaces. It is an important tool for studying the cluster behaviour on the substrates. We have deposited gold (Au) on the substrates of mica and silicon (Si) in a high vacuum chamber. The thickness of thin films is about 50-500 A. The samples are taken out from the chamber and put into the sample holder of the STM. We analysed these samples in air at room temperature. We have observed gold cluster structures and motion behaviour on the (001) plane of mica which cleaved in air. The thickness of gold thin film is about 400 A. On this thin film, there are clusters and these clusters move randomly with time. Similarly we observed gold clusters on one (111) plane of the Si wafer. Before depositing the gold thin film, we cleaned the Si wafer with a chemical clean technique. The thickness of gold thin films is about 50-400 A. On the (111) plane of the Si wafer, gold clusters also move randomly with time. We analysed these samples with Auger electron spectroscopy (AES) and scanning electron microscopy (SEM). After that, we discuss these results and the random motion mechanism of these clusters.
Investigation of the interface of a HgCdTe/CdTe thin film grown by MOCVD
Zheng Tianshui, Liu Liying, Xing Zhongjing, Wang Wencheng, Shen Yuanlma and Zhang Zhiming, Laboratory of Laser Physics
K J Ma, Z Z Yu, J Q Yong and S Z Shen, Shanghai Institute of
and Optics, Department of Physics, Fudan University, Shanghai 200433, China
and Song Xiang-yun, Shanghai Institute of Ceramics, Academia
Technical Physics, Academia Sinica, Shanghai 200083, China; Sinica, Shanghai 200050, China
Four to six monolayers of AISt3 Langmuir-Blodgett (L-B) film and one layer of thermal deposited 3.5-6 nm-thick A1203 film alternatively form a hybrid A1St3/A1203 modulated multilayer
The interface of a HgCdTe/CdTe thin film grown by MOCVD was investigated by high resolution electron microscopy. It is 1073
and X R D measurements show that there are serious interdiffusion and interface reactions in samples annealed at temperatures higher than 650°C. The possible reaction products are Ba2SiO4 and Ba3SiOs. No new chemical compound related to copper was found. RBS measurements show that Cu ions diffused deeply into Si(100) substrate and play the role of a fast diffuser and Ba ions are concentrated in an area near the interface. The result of AES measurement is in agreement with that of RBS measurements. A thin layer of ZrO2 may slow down the interdiffusion process significantly.
structure. The infrared spectrum of AISt3 monolayers in the multilayer has been measured by Fourier transform infrared spectroscopy monolayers. The absorption intensity of CH2 stretching vibration vs AISt3 layer number is compared with optical multilayer calculation. The periodic structure of the hybrid multilayer is revealed by low angle X-ray diffraction. These show that the arrangement of A1St3 film deposited on a new solid surface of A1203 film is the same as that on the initial substrate surface. It is suggested that this method for building a L-B film/alumina multilayer structure could be applied to the study of nonlinear optical properties of Langmuir-Blodgett films.
The tantalum/aluminum alloy resistive film containing aluminum 50 at% Study of behaviour of metal clusters on substrates with STM Yang Bangchao and Jia Yuming, University of Electronic Science
and Technology of Chengdu, Chengdu 610054, China In this paper, both the tantalum/aluminum alloy resistive film containing aluminum 50 at% and the mid-power thin-film attenuator used for microwave circuits are studied and analyzed. The Ta/A1 alloy film containing A1 50 at% has high resistance stability. The alloy film is deposited by sputtering from a tantalum cathode which is covered partly by aluminum discs. The aluminum part of the target area is approximately 43% of the total. It is found that the alloy film could be used for a stable power resistor and its network. The main properties of the resistor as follows : atomic content Ta:A1 = 53.7:46.3; specific resistivity, 150-300 # ~ cm; temperature coefficient of resistance - 7 0 + 2 0 ppm '~C- ~; aged at 200°C for 96 h R/R < 0.3% ; and temperature circle ( - 1 0 to +200°C/5 times) R/R < 0.5%. The mid-power thin film attenuator used for microwave circuits is also described in this paper. This attenuator is made from the Ta/A1 alloy film containing aluminum 50 at%. The formula derived for attenuation and characteristic impedance of attenuator with n-tape network pattern will prove to be of benefit for the design of thin-film attenuators. The design of power or midpower thin-film attenuator has been discussed. Finally, the fabrication and assembly of the attenuator have been introduced. The indexes of the annenuator are : dimension 13.86 x 13.40 x 0.60 mm; power loading 25 W ; average power density 1.75 W mm 2; maximum power density 3.8 W m m - 2 ; attenuation 11.5 dB; characteristic impedance 50; frequency range 0-540 MHz ; and voltage standing-wave ratio < 1.08. The results above indicate that the mid-power thin-film attenuator has satisfied the demands of the user completely and it has not been previously reported in our country.
Study of CH2 stretching vibration in AISt3 L-B film/alumina hybrid multilayer by infrared spectroscopy
Wang Dongsheng, Ma Zili, Xue Zengquan and Wu Quande,
Department of Radio-Electronics, Peking University and Beo'ing Laboralory of Vacuum Physics, Academia Sinica, Beo'ing 100871, China Clusters are small particles whose size is less than l 0 3 /~. They possess special characteristics compared with the same bulk element material. Sometimes we find some clusters on the deposited thin films. These clusters will affect the structures and characteristics of the films, especially in semiconductor devices, where they will affect device quality. A scanning tunnelling microscope (STM) possesses atom level resolution for analysing sample surfaces. It is an important tool for studying the cluster behaviour on the substrates. We have deposited gold (Au) on the substrates of mica and silicon (Si) in a high vacuum chamber. The thickness of thin films is about 50-500 A. The samples are taken out from the chamber and put into the sample holder of the STM. We analysed these samples in air at room temperature. We have observed gold cluster structures and motion behaviour on the (001) plane of mica which cleaved in air. The thickness of gold thin film is about 400 A. On this thin film, there are clusters and these clusters move randomly with time. Similarly we observed gold clusters on one (111) plane of the Si wafer. Before depositing the gold thin film, we cleaned the Si wafer with a chemical clean technique. The thickness of gold thin films is about 50-400 A. On the (111) plane of the Si wafer, gold clusters also move randomly with time. We analysed these samples with Auger electron spectroscopy (AES) and scanning electron microscopy (SEM). After that, we discuss these results and the random motion mechanism of these clusters.
Investigation of the interface of a HgCdTe/CdTe thin film grown by MOCVD
Zheng Tianshui, Liu Liying, Xing Zhongjing, Wang Wencheng, Shen Yuanlma and Zhang Zhiming, Laboratory of Laser Physics
K J Ma, Z Z Yu, J Q Yong and S Z Shen, Shanghai Institute of
and Optics, Department of Physics, Fudan University, Shanghai 200433, China
and Song Xiang-yun, Shanghai Institute of Ceramics, Academia
Technical Physics, Academia Sinica, Shanghai 200083, China; Sinica, Shanghai 200050, China
Four to six monolayers of AISt3 Langmuir-Blodgett (L-B) film and one layer of thermal deposited 3.5-6 nm-thick A1203 film alternatively form a hybrid A1St3/A1203 modulated multilayer
The interface of a HgCdTe/CdTe thin film grown by MOCVD was investigated by high resolution electron microscopy. It is 1073