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Evaluation of Si ribbon crystals for solar cells
Comparative studies of photoresist processing of microelectronics regarding chemical pollution, shortage and cost K. R I T C t t l E and H. G. HUGHES
Solid State Technology, p.45 (February 1976). As the microelectronics industry continuously becomes more complex and sophisticated in device fabrication, photolithographic technology is faced with resolution limitations, economic considerations, pollution, and shortages of chemicals. The latter problems are seriously affecting all phases of the semiconductor wafer process. In this report the photoresist process is emphasised with respect to cost consideration, pollution and chemical shortages. Commonly used solvents in photoresist processing, such as esters, aromatics, and olefinic organics were replaced with saturated hydrocarbon solvents without sacrificing the photoresist performance. The solvents used were readily available during the recent energy crisis as opposed to the lack of availability of those more commonly used in the industry. Detection of molecular films by harmonic generation of surface acoustic waves
C. D. W. WILKINSON, P. F. HEIDRICH and E. G. LEAN Proceedings of the 8th Conference (1976 International) on Solid State Devices, Tokyo, 1976; Japanese Journal of Applied Physics, 16, Supplement 16-1, pp.523-525 (1977). We have applied the technique of thin film detection by harmonic generation of dispersive Rayleigh waves I to detect molecular layers of stearie acid and Ti diffused layers on LiNbO 3 substrates. The technique is based on the loading of a thin film on an ideal substrate whih causes the velocity dispersion between the fundamental of a Rayleigh wave and its second harmonic. This dispersion causes sinusoidal oscillation of the second harmonic intensity as a function of interaction length. Using an optical probe to measure the diffracted light by the surface wave second harmonic along the propagation direction, the velocity variation between the fundamental and the second harmonic due to the film can easily be measured.
The structure of cleaned and polished (100) GaAs surfaces B. L. WEISS and H. L. H A R T N A G E L Int. J. Electronics, 41(4), p.185 (1976). Results are presented here which show that after cleaning in organic solvents, polishing with Br-methanol solution and etching in HCI, all GaAs samples have a residual thin layer of oxide on their surfaces. Theory of iron-group impurities in II-VI compounds S. W. BIERNACKI J. Phys. Chem. Solids, 37, p.819 (1976). A new method is developed for the description of the electronic 3d levels of the paramagnetie impurities in II-VI compounds. The method is based upon the linear-combination-of-atomic-orbitals approximation. The effective one-electron Hamiltonian, taken as a sum of the kinetic energy, the interaction energy with nuclei, and the interaction energy with spatial distribution of the electrons, employs one adjustable parameter. This parameter takes into account some redistribution of the electron density in the crystal. The relationship between the method presented and the molecular orbital and pseudopotential methods is discussed. The method is applied to the cases of Sc2+, T~ + and Co2+ in ZnS, and Co 2+ in ZnSe. The cubic field splitting parameter A and the position of impurity levels with respect to the valence band is calculated within the frame of the one-electron approximation. Valley degeneracy of electrons in accumulation and inversion layers on Si(111) surface D. C. TSUI and G. KAM1NSKY Solid State Communications, 20, p.93 (1976). We report three experiments exploring the valley degeneracy of electrons in n-channel MOSFETs on the S i ( l l l ) surface. The results sugest that the reduction of the valley degeneracy from 6 to 2 can be explained by the existence of highly stressed domains at the Si-SiO2 interface. The stress, being much too large for those known from thermal mismatch between Si-SiO2, is attributed to mismatch between te Si-Si bonds in Si and the Si-O-Si bonds in SiO 2. Evaluation of Si ribbon crystals for solar cells A. H O J O , Y. IKAWA, T. MATSUI and M. N A G A G A W A Proceedings of the 8th Conference (1976 International) on Solid State Devices, Tokyo, 1976; Japanese Journal of Applied Physics, 16, Supplement 16-1, pp.407-412 (1977).
Defect structures, electrical properties of the Si ribbon crystals were investigated. Performances of Si ribbon solar cells were also measured. It was found that twin boundaries did not degrade the electrical properties. Whereas irregular boundaries deteriorated the minority carrier lifetime appreciably. The solar cells fabricated from the ribbon crystals did not show inferior properties in spite of the existence of the defects in the crystals when the surface contact was kept off the SiC particles embedded in the ribbon surface.
High-field transport in NiO and Nil_xLixO thin films N. FUSCHILLO, B. LALEVIC and B. LEUNG
Solid State Electronics, 19, p.209 (1976). Repetitive switching from the high- to the low-resistance state in thin films of NiO and Ni l_xLixO with Ni electrodes is investigated in the doping range from 0 to 0.4 at% Li. As the ~oitage is increased, four different I.V characteristics are obtained in succession: (1) an initial high-resistance state, which exhibits at first zero and then quadratic dependence of conductivity on the applied electric field; (2) a second lower-resistance state with linear and the cubic I-V characteristics followed by an avalanche-like behaviour displaying a pronounced current-controlled negative resistance; (3) a third low-resistance state; and (4) a final metallic state, corresponding to irreversible dielectric breakdown. The states are reversible and show cyclic switching behaviour, exhibiting a voltage-dependent delay time. Transport and dielectric data as a function of Li content, voltage, frequency, and temperature are used to propose a model for the switching mechanism.
The electronic properties of epitaxial layers. Part 1 H. F. MATARE
Solid State Technology, p.25 (January 1976). In this first instalment of a series of articles on epitaxial layers, the problems of thin-film surface structure, bond strength and type, and electronic features are discussed with respect to metal-metal and metal-insulator layers. It is shown that epitaxial relations are of minor importance in these cases. This is followed by a discussion of the hetero-epitaxial cases, metal-semiconductor and insulatorsemiconductor are discussed with special reference to silicon on sapphire. Possible measures to improve perfection in the latter case are mentioned. Homo- and hetero-epitaxy in the case of semiconductor-semiconductor layers is treated. Far-infrared absorption of large electron-hole drops in stressed C,e R. L. A U R B A C H , L. EAVES, R. S. MARKIEWICZ and P. L. RICHARDS SolidState Communications, 19, p.1023 (1976). The far-infrared attenuation spectrum due to a large electron-hole drop in inhomogeneously stressed Ge has been measured and compared to the attenuation by small drops in unstressed Go. The spectrum is analysed using the full Mie theory for the absorption due to a large sphere; the experimental results are interpreted as bulk plasma absorption in a drop with pair density considerably lowered by the strain. Density of states determination of mixed semiconductors by neutron diffraction R. BESERMAN, M. ZIGONE, W. DREXEL and C. MARTI Solid State Communications, 18(3), p.419 (1976). The phonon density of states of mixed crystals has been determined by neutron diffraction in powders. In the 'two mode type' mixed crystal ZnSxSel_x, the great features of the host lattice density of states, are not modified up to an 'impurity' concentration of 25%. On the other hand, the presence of To in ZnSezTet_Xwith x=0.25, give rise to a 'one mode type' mixed crystal, the density of states of which is an average of that of the two components. The electronic properties of epltaxial layers H. F. M A T A R E Solid State Technology, p.36 (February 1976). The particular case and the reasons for the excellent properties for radiative recombinations are outlined. The particular features of the GaxAll_xAs/GaAs junction with respect to dopant concentration and. stoichiometry are considered and the influence of the temperature gradient for large size melts during liquid epitaxy is shown. A typical case of the chemical analysis of epitaxial layers using a microprobe is discussed. Layer stoichiometry can also be derived from measurements of photoluminescence and a refined method using modulated light injection combined with a double monochromator set-up is described. Furthermore, the wealth of available particle-injection methods (ions, electrons, nucleons, infrared radiation, molecular 67
Solid State Technology, p.45 (February 1976). As the microelectronics industry continuously becomes more complex and sophisticated in device fabrication, photolithographic technology is faced with resolution limitations, economic considerations, pollution, and shortages of chemicals. The latter problems are seriously affecting all phases of the semiconductor wafer process. In this report the photoresist process is emphasised with respect to cost consideration, pollution and chemical shortages. Commonly used solvents in photoresist processing, such as esters, aromatics, and olefinic organics were replaced with saturated hydrocarbon solvents without sacrificing the photoresist performance. The solvents used were readily available during the recent energy crisis as opposed to the lack of availability of those more commonly used in the industry. Detection of molecular films by harmonic generation of surface acoustic waves
C. D. W. WILKINSON, P. F. HEIDRICH and E. G. LEAN Proceedings of the 8th Conference (1976 International) on Solid State Devices, Tokyo, 1976; Japanese Journal of Applied Physics, 16, Supplement 16-1, pp.523-525 (1977). We have applied the technique of thin film detection by harmonic generation of dispersive Rayleigh waves I to detect molecular layers of stearie acid and Ti diffused layers on LiNbO 3 substrates. The technique is based on the loading of a thin film on an ideal substrate whih causes the velocity dispersion between the fundamental of a Rayleigh wave and its second harmonic. This dispersion causes sinusoidal oscillation of the second harmonic intensity as a function of interaction length. Using an optical probe to measure the diffracted light by the surface wave second harmonic along the propagation direction, the velocity variation between the fundamental and the second harmonic due to the film can easily be measured.
The structure of cleaned and polished (100) GaAs surfaces B. L. WEISS and H. L. H A R T N A G E L Int. J. Electronics, 41(4), p.185 (1976). Results are presented here which show that after cleaning in organic solvents, polishing with Br-methanol solution and etching in HCI, all GaAs samples have a residual thin layer of oxide on their surfaces. Theory of iron-group impurities in II-VI compounds S. W. BIERNACKI J. Phys. Chem. Solids, 37, p.819 (1976). A new method is developed for the description of the electronic 3d levels of the paramagnetie impurities in II-VI compounds. The method is based upon the linear-combination-of-atomic-orbitals approximation. The effective one-electron Hamiltonian, taken as a sum of the kinetic energy, the interaction energy with nuclei, and the interaction energy with spatial distribution of the electrons, employs one adjustable parameter. This parameter takes into account some redistribution of the electron density in the crystal. The relationship between the method presented and the molecular orbital and pseudopotential methods is discussed. The method is applied to the cases of Sc2+, T~ + and Co2+ in ZnS, and Co 2+ in ZnSe. The cubic field splitting parameter A and the position of impurity levels with respect to the valence band is calculated within the frame of the one-electron approximation. Valley degeneracy of electrons in accumulation and inversion layers on Si(111) surface D. C. TSUI and G. KAM1NSKY Solid State Communications, 20, p.93 (1976). We report three experiments exploring the valley degeneracy of electrons in n-channel MOSFETs on the S i ( l l l ) surface. The results sugest that the reduction of the valley degeneracy from 6 to 2 can be explained by the existence of highly stressed domains at the Si-SiO2 interface. The stress, being much too large for those known from thermal mismatch between Si-SiO2, is attributed to mismatch between te Si-Si bonds in Si and the Si-O-Si bonds in SiO 2. Evaluation of Si ribbon crystals for solar cells A. H O J O , Y. IKAWA, T. MATSUI and M. N A G A G A W A Proceedings of the 8th Conference (1976 International) on Solid State Devices, Tokyo, 1976; Japanese Journal of Applied Physics, 16, Supplement 16-1, pp.407-412 (1977).
Defect structures, electrical properties of the Si ribbon crystals were investigated. Performances of Si ribbon solar cells were also measured. It was found that twin boundaries did not degrade the electrical properties. Whereas irregular boundaries deteriorated the minority carrier lifetime appreciably. The solar cells fabricated from the ribbon crystals did not show inferior properties in spite of the existence of the defects in the crystals when the surface contact was kept off the SiC particles embedded in the ribbon surface.
High-field transport in NiO and Nil_xLixO thin films N. FUSCHILLO, B. LALEVIC and B. LEUNG
Solid State Electronics, 19, p.209 (1976). Repetitive switching from the high- to the low-resistance state in thin films of NiO and Ni l_xLixO with Ni electrodes is investigated in the doping range from 0 to 0.4 at% Li. As the ~oitage is increased, four different I.V characteristics are obtained in succession: (1) an initial high-resistance state, which exhibits at first zero and then quadratic dependence of conductivity on the applied electric field; (2) a second lower-resistance state with linear and the cubic I-V characteristics followed by an avalanche-like behaviour displaying a pronounced current-controlled negative resistance; (3) a third low-resistance state; and (4) a final metallic state, corresponding to irreversible dielectric breakdown. The states are reversible and show cyclic switching behaviour, exhibiting a voltage-dependent delay time. Transport and dielectric data as a function of Li content, voltage, frequency, and temperature are used to propose a model for the switching mechanism.
The electronic properties of epitaxial layers. Part 1 H. F. MATARE
Solid State Technology, p.25 (January 1976). In this first instalment of a series of articles on epitaxial layers, the problems of thin-film surface structure, bond strength and type, and electronic features are discussed with respect to metal-metal and metal-insulator layers. It is shown that epitaxial relations are of minor importance in these cases. This is followed by a discussion of the hetero-epitaxial cases, metal-semiconductor and insulatorsemiconductor are discussed with special reference to silicon on sapphire. Possible measures to improve perfection in the latter case are mentioned. Homo- and hetero-epitaxy in the case of semiconductor-semiconductor layers is treated. Far-infrared absorption of large electron-hole drops in stressed C,e R. L. A U R B A C H , L. EAVES, R. S. MARKIEWICZ and P. L. RICHARDS SolidState Communications, 19, p.1023 (1976). The far-infrared attenuation spectrum due to a large electron-hole drop in inhomogeneously stressed Ge has been measured and compared to the attenuation by small drops in unstressed Go. The spectrum is analysed using the full Mie theory for the absorption due to a large sphere; the experimental results are interpreted as bulk plasma absorption in a drop with pair density considerably lowered by the strain. Density of states determination of mixed semiconductors by neutron diffraction R. BESERMAN, M. ZIGONE, W. DREXEL and C. MARTI Solid State Communications, 18(3), p.419 (1976). The phonon density of states of mixed crystals has been determined by neutron diffraction in powders. In the 'two mode type' mixed crystal ZnSxSel_x, the great features of the host lattice density of states, are not modified up to an 'impurity' concentration of 25%. On the other hand, the presence of To in ZnSezTet_Xwith x=0.25, give rise to a 'one mode type' mixed crystal, the density of states of which is an average of that of the two components. The electronic properties of epltaxial layers H. F. M A T A R E Solid State Technology, p.36 (February 1976). The particular case and the reasons for the excellent properties for radiative recombinations are outlined. The particular features of the GaxAll_xAs/GaAs junction with respect to dopant concentration and. stoichiometry are considered and the influence of the temperature gradient for large size melts during liquid epitaxy is shown. A typical case of the chemical analysis of epitaxial layers using a microprobe is discussed. Layer stoichiometry can also be derived from measurements of photoluminescence and a refined method using modulated light injection combined with a double monochromator set-up is described. Furthermore, the wealth of available particle-injection methods (ions, electrons, nucleons, infrared radiation, molecular 67