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The characteristics of thermal grown silicon oxide film
150
WORLD
ABSTRACTS
ON MICROELECTRONICS
reported. A method for determining, in nearly the whole energy gap, the distribution of energy levels and time constants of interface states is presented. The sensitivity is sufficient to allow an investigation of interface states even in unirradieted transistors. The measured distribution, P(~), of the time constants of the slow interface states, ~, is approximately of the form 1/~ and thus explains the appearance of a 1If noise power spectrum. Interpreting the observed phenomena with a semiclassical tunnelling model leads to the conclusion that the spatial distribution of the slow interface states is fairly constant throughout the first 20 A from the interface into the oxide layer.
The c h a r a c t e r i s t i c s o f t h e r m a l g r o w n s i l i c o n o x i d e film. K. ONO, Y. SUNOHA~ and T. INotrs, Trans. Inst. Electron. Commun. Engrs yapan 53-C, No. 10, October (1970), p. 724. (In Japanese.) The author reports the results of investigations concerned with relations between the electrical characteristics and the fabrication conditions of silicon dioxide films. The oxide fabricated at near 1100°C oxidation temperature has the highest concentration of SiOs. Adding to the above, the breakdown voltage characteristics of the silicon dioxide films and the flatness of the film surface for an oxidation temperature of 1100°C were relatively good. On the other hand, the electron diffraction patterns obtained from the silicon surfaces with the oxide etched-off showed clear differences depending on the oxidation atmosphere. planar diodes were fabricated using these oxides.
Negative differential conductivity in s e m i c o n ductors. J. C. McG~oDnY, Proc. lOth International Conf. on the Physics of Semiconductors (CONF-700801). Massachusetts Institute of Technology, Cambridge, Mass., USA, 17-21 August (1970). This paper is a review of recent progress in field-controlled high frequency negative differential conductivity effects in semiconductors. Topics discussed include the following. Studies of the Gunn effect and cartier multiplication in n-InSb under hydrostatic pressure which have yielded interesting results on bandstructure conditions for the Gunn effect. The interpretation of the results yields both the position and symmetry of the higher lying conduction bands. Studies of alloys in the system GazIn£'zSb as low threshold field Gunn effect materials. The bandstructure of these materials has been studied by a variety of techniques, and the high field transport interpreted in terms of the bandstructure. Transverse negative differential conductivity effects which have been studied experimentally and theoretically in n-Ge. Gunn effects in p-type materials, when the valence band has been split by strain. D o u b l e i n j e c t i o n in s e m i c o n d u c t o r s h e a v i l y d o p e d w i t h d e e p t w o - l e v e l traps. W. H. Wlmea and G. W. FORD, Solid-State Electron. 13 (1970), p. 1333. Double injection is discussed for semiconductors heavily doped with deep recombination centers which act both as aceeptors and donors. The current-voltage characteristies are derived uswg a generalization of the method due
AND RELIABILITY
to Lampert for long structures in which diffusion can be neglected. Thermal emission from the traps and trapped space-charge effects are included. The resulting j - V curve shows in order of increasing current the following general features: an ohmic regime, a low injection square law related to thermal emission, a negative resistance regime, a high injection square law and finally a spacecharge-limited cube law. A complete computer solution for the case of gold-doped silicon is given. Simple power laws for the various regimes, derived using the quasineutrality approximation, are found to agree well with the numerical solution. An expression is obtained for the voltage at the threshold of the negative resistance, and the effects of field dependant mobility are discussed quantitatively. Experimental results are presented for long (,~1001au) gold-doped (-.~100Xecm -s) silicon p - / - n structures. The devices are fabricated from high purity n-type silicon, and large area alloy junctions are used. Pulsed I - V messuremants at room temperature show an ohmic regime, a square-law regime and a negative resistance regime. These data are found to agree quantitatively with the theoretical calculations up to and including the onset of the negative resistance. In particular a strong temperature dependance is observed in the low injection square-law regime, which is different from that found in the ohmic regime. This difference is explained in terms of the level structure of the gold impurity. The current for voltages above the onset of the negative resistance is approximately two orders of magnitude below the theoretical predictions. This indicates that filamentary conduction is probably occurring. ~eisen c o n s t a n t of s o m e s e m i c o n d u c t o r s . J. K. D. V~mMA and M. D. AG~ARWAL, Solid State Commun. 8 (1970), p, 1929. The average value of the Grtineisen constant for I I I - V and I I - V I groups of semiconductors have been evaluated. This agrees fairly well with the value obtained from lattice thermal conductivity data. This value, however, is considerably larger than that obtained from Grtineisen relation. C o v a l e n t bonds in wemicmm~luctors. J. C. PHILLIPS, Proc. lOth lnter, aHonal Conf. on the Physics of Semiconductors (CONF-700801). Massachusetts Institute of Technology, Cambridge, Mass., USA, 17-21 August (1970). Modernized theories of covalent bonding are discussed, with special reference to tetrahedrally coordinated AnBs-n semiconductors. Spectroscopic definitions are given of electro-negativity, ionicity and the tendency towards metallization with increasing atomic number. The spectroscopic definitions permit quantitative discussion of crystal s t r u ~ r e s , heats of formation, miscibility limits of pseudo-binary alloys, long wavelength limits of acoustic and optic interaotmic forces, deformation potentials, interband energy differences and ionization potentials, impurity binding energies and g factors, non-linear optical smu:eptibilities, piezoelectric constants and other constitutive properties. Conne~ions with
WORLD
ABSTRACTS
ON MICROELECTRONICS
reported. A method for determining, in nearly the whole energy gap, the distribution of energy levels and time constants of interface states is presented. The sensitivity is sufficient to allow an investigation of interface states even in unirradieted transistors. The measured distribution, P(~), of the time constants of the slow interface states, ~, is approximately of the form 1/~ and thus explains the appearance of a 1If noise power spectrum. Interpreting the observed phenomena with a semiclassical tunnelling model leads to the conclusion that the spatial distribution of the slow interface states is fairly constant throughout the first 20 A from the interface into the oxide layer.
The c h a r a c t e r i s t i c s o f t h e r m a l g r o w n s i l i c o n o x i d e film. K. ONO, Y. SUNOHA~ and T. INotrs, Trans. Inst. Electron. Commun. Engrs yapan 53-C, No. 10, October (1970), p. 724. (In Japanese.) The author reports the results of investigations concerned with relations between the electrical characteristics and the fabrication conditions of silicon dioxide films. The oxide fabricated at near 1100°C oxidation temperature has the highest concentration of SiOs. Adding to the above, the breakdown voltage characteristics of the silicon dioxide films and the flatness of the film surface for an oxidation temperature of 1100°C were relatively good. On the other hand, the electron diffraction patterns obtained from the silicon surfaces with the oxide etched-off showed clear differences depending on the oxidation atmosphere. planar diodes were fabricated using these oxides.
Negative differential conductivity in s e m i c o n ductors. J. C. McG~oDnY, Proc. lOth International Conf. on the Physics of Semiconductors (CONF-700801). Massachusetts Institute of Technology, Cambridge, Mass., USA, 17-21 August (1970). This paper is a review of recent progress in field-controlled high frequency negative differential conductivity effects in semiconductors. Topics discussed include the following. Studies of the Gunn effect and cartier multiplication in n-InSb under hydrostatic pressure which have yielded interesting results on bandstructure conditions for the Gunn effect. The interpretation of the results yields both the position and symmetry of the higher lying conduction bands. Studies of alloys in the system GazIn£'zSb as low threshold field Gunn effect materials. The bandstructure of these materials has been studied by a variety of techniques, and the high field transport interpreted in terms of the bandstructure. Transverse negative differential conductivity effects which have been studied experimentally and theoretically in n-Ge. Gunn effects in p-type materials, when the valence band has been split by strain. D o u b l e i n j e c t i o n in s e m i c o n d u c t o r s h e a v i l y d o p e d w i t h d e e p t w o - l e v e l traps. W. H. Wlmea and G. W. FORD, Solid-State Electron. 13 (1970), p. 1333. Double injection is discussed for semiconductors heavily doped with deep recombination centers which act both as aceeptors and donors. The current-voltage characteristies are derived uswg a generalization of the method due
AND RELIABILITY
to Lampert for long structures in which diffusion can be neglected. Thermal emission from the traps and trapped space-charge effects are included. The resulting j - V curve shows in order of increasing current the following general features: an ohmic regime, a low injection square law related to thermal emission, a negative resistance regime, a high injection square law and finally a spacecharge-limited cube law. A complete computer solution for the case of gold-doped silicon is given. Simple power laws for the various regimes, derived using the quasineutrality approximation, are found to agree well with the numerical solution. An expression is obtained for the voltage at the threshold of the negative resistance, and the effects of field dependant mobility are discussed quantitatively. Experimental results are presented for long (,~1001au) gold-doped (-.~100Xecm -s) silicon p - / - n structures. The devices are fabricated from high purity n-type silicon, and large area alloy junctions are used. Pulsed I - V messuremants at room temperature show an ohmic regime, a square-law regime and a negative resistance regime. These data are found to agree quantitatively with the theoretical calculations up to and including the onset of the negative resistance. In particular a strong temperature dependance is observed in the low injection square-law regime, which is different from that found in the ohmic regime. This difference is explained in terms of the level structure of the gold impurity. The current for voltages above the onset of the negative resistance is approximately two orders of magnitude below the theoretical predictions. This indicates that filamentary conduction is probably occurring. ~eisen c o n s t a n t of s o m e s e m i c o n d u c t o r s . J. K. D. V~mMA and M. D. AG~ARWAL, Solid State Commun. 8 (1970), p, 1929. The average value of the Grtineisen constant for I I I - V and I I - V I groups of semiconductors have been evaluated. This agrees fairly well with the value obtained from lattice thermal conductivity data. This value, however, is considerably larger than that obtained from Grtineisen relation. C o v a l e n t bonds in wemicmm~luctors. J. C. PHILLIPS, Proc. lOth lnter, aHonal Conf. on the Physics of Semiconductors (CONF-700801). Massachusetts Institute of Technology, Cambridge, Mass., USA, 17-21 August (1970). Modernized theories of covalent bonding are discussed, with special reference to tetrahedrally coordinated AnBs-n semiconductors. Spectroscopic definitions are given of electro-negativity, ionicity and the tendency towards metallization with increasing atomic number. The spectroscopic definitions permit quantitative discussion of crystal s t r u ~ r e s , heats of formation, miscibility limits of pseudo-binary alloys, long wavelength limits of acoustic and optic interaotmic forces, deformation potentials, interband energy differences and ionization potentials, impurity binding energies and g factors, non-linear optical smu:eptibilities, piezoelectric constants and other constitutive properties. Conne~ions with