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Measuring semi-conductor properties of thermoelectric materials
80
World Abstracts on Microelectronics and Reliability
moderate cost. They offer higher power than conventional 1C op amps, and they enable you to minimize the use of discrete components. Quad-linear ICs racing up the pike, paced by automotive applications. N. K. OSBRINK. Electronic Design 32 (11 Oct. 1973). Quad-linear ICs, spawned by the special needs of the automotive industry for low-cost, highly reliable electronic devices, are rapidly becoming popular not only a m o n g linear-circuit designers but a m o n g digital as well. These four-in-one circuits be they op a m p s , c o m p a r a t o r s or Norton amplifiers are being used in increasing quantities in antiskid, fuel-injection and emission-control circuits, all of which require low power, dependable ICs. One industry sourcc has estimated thai the automotive market for quads will reach lO-million a m o n t h after next March.
7. S E M I C O N D U C T O R
INTEGRATED
Metal semiconductor contact: resistivity and noise. J. P. NOUGIER and M. ROLLAND. Solid St. Electron. 16, 1399 (1973) A new method is given for determining simultaneously bulk and contact resistivities of cruciform samples. A method is given for deducing high electric field bulk conductivity from measurements performed on samples with noninjective but resistive contacts. It is shown that the contact excess noise current spectral density is proportional to r, v l / j2 dE d£ 1
and that this law remains valid up to 500 M H z and 80 A cm 2. A new method is given for characterizing noise contact at a fixed frequency. A fabrication technique which provides ohmic contacts to p-type germanium is described. Metal-germanium Schottky barriers. A. THANAILAKIS and D. C. NORTHROP. Solid St. Electron. 16, 1383 (1973). A systematic study has been made of the electrical characteristics of Schottky barriers fabricated by evaporating various metal films on n-type chemically cleaned germanium substrates. The diodes, with the exception of AI Ge contacts, exhibit near-ideal electrical characteristics and age only slightly towards lower barrier height values. A1-Ge contacts exhibit very pronounced ageing towards higher barrier height values, due to formation of an extra aluminium oxide interfacial layer. Because of this, the barrier height values of aged AI Ge contacts derived from I V and C V characteristics differ significantly. The dependence of the barrier height, (qSb) on the metal work function, q5m, for different metal germanium contacts shows that surface states play an important role in the formation of the barrier. The densit2, of germanium surface states is estimated to be D , - - 2 × lOl3eV ~cm 2. Surface charge and stress in the Si/SiO 2 system. S. D. BROTHERrON, T. G. READ, D. R. LAMa and A. F. W. WH3.OUGHBY. Solid St. Electron. 16, 1367 (1973). A model for the stress distribution in thermally oxidised silicon slices has been developed using beam theory and bimetallic strip theory. The stresses have been confirmed by making lattice parameter measurements on oxidised silicon using the APEX X-ray diffraction technique. The often suggested relationship between the surface charge density at the Si/SiO 2 interface and the stress in the silicon surface has
IC monostable SN74121 for easier detection of IR pulsed lasers. S. NEELAKANTAN and L. C. MANOHARAN. Int. J. Electron. 36, 279 (1974). A novel circuit using a digital IC monostable multivibrator for the detection of very narrow pulses using an ordinary oscilloscope is described in this research note.
Data processing, LSI will help to bring sight to the blind. Staff of The Neuroprostheses Program, University of Utah. Electronics 81 (24 Jan. 1974). Data from semiconductor camera in an artificial eye will be processed by circuitry held in spectacle frame, then transmitted to an array of electrodes implanted in a blind person's brain to evoke images.
CIRCUITS,
DEVICES
AND MATERIALS
been investigated and shown to be inconsistent. Finally, analysis of the variation of surface charge density with oxide thickness has caused us to postulate the presence of both positively and negatively charged centres at the interface. Effects of temperature on current instabilities caused by recombination centers in semiconductors. A R ELSHARKAWI and K. C. KAO. Solid St. Electron. 16, 1355 (1973). With the carrier distribution function approximated by a displaced Maxwellian function the current voltage characteristics for a semiconductor containing repulsive Coulomb recombination centers have been derived, and the current instabilities in n-GaAs as functions of temperature and applied field have been experimentally studied. The experimental results show that the threshold current for the onset of the current instabilities is not sensitive to temperature, but the corresponding threshold field decreases with increasing temperature; and that the current oscillation frequency increases and the amplitude decreases with increasing temperature. These results are in good agreement with the theory. Measuring semi-conductor properties of thermoelectric materials. D. J. RYDEN. Electronic Engng 59 (1974). An outline of the various measurements is given but the main purpose of this work is to describe those aspects which experience has shown to be a problem. A number of the points raised are not adequately covered in current text books on the subject. Redistribution and anisotropic diffusion of boron in (I00) and (111) oriented silicon. G. MASETTI, P. NEGRINI and S. SOLMI. Alta Frequenza XLII, 626 (Nov. 1973). The redistribution and the anisotropic diffusion of boron in ( I 11 ) and (100) oriented silicon have been experimentally studied at the temperature of 1100°C, in a large variety of oxidizing atmospheres and for times ranging from 15 min up to 9 hr. The boron diffused layers have been analyzed using a theoretical model, earlier presented by the authors, which correctly takes into account the redistribution phenomena at the oxide-silicon interface. In this way it has been demonstrated that the boron segregation coefficient is independent by the silicon orientation, and the anisotropic behaviour of boron diffusion in (100) silicon, only depends by the presence of oxygen within the drive-in atmosphere. These conclusions, together with the results of X-ray topography
World Abstracts on Microelectronics and Reliability
moderate cost. They offer higher power than conventional 1C op amps, and they enable you to minimize the use of discrete components. Quad-linear ICs racing up the pike, paced by automotive applications. N. K. OSBRINK. Electronic Design 32 (11 Oct. 1973). Quad-linear ICs, spawned by the special needs of the automotive industry for low-cost, highly reliable electronic devices, are rapidly becoming popular not only a m o n g linear-circuit designers but a m o n g digital as well. These four-in-one circuits be they op a m p s , c o m p a r a t o r s or Norton amplifiers are being used in increasing quantities in antiskid, fuel-injection and emission-control circuits, all of which require low power, dependable ICs. One industry sourcc has estimated thai the automotive market for quads will reach lO-million a m o n t h after next March.
7. S E M I C O N D U C T O R
INTEGRATED
Metal semiconductor contact: resistivity and noise. J. P. NOUGIER and M. ROLLAND. Solid St. Electron. 16, 1399 (1973) A new method is given for determining simultaneously bulk and contact resistivities of cruciform samples. A method is given for deducing high electric field bulk conductivity from measurements performed on samples with noninjective but resistive contacts. It is shown that the contact excess noise current spectral density is proportional to r, v l / j2 dE d£ 1
and that this law remains valid up to 500 M H z and 80 A cm 2. A new method is given for characterizing noise contact at a fixed frequency. A fabrication technique which provides ohmic contacts to p-type germanium is described. Metal-germanium Schottky barriers. A. THANAILAKIS and D. C. NORTHROP. Solid St. Electron. 16, 1383 (1973). A systematic study has been made of the electrical characteristics of Schottky barriers fabricated by evaporating various metal films on n-type chemically cleaned germanium substrates. The diodes, with the exception of AI Ge contacts, exhibit near-ideal electrical characteristics and age only slightly towards lower barrier height values. A1-Ge contacts exhibit very pronounced ageing towards higher barrier height values, due to formation of an extra aluminium oxide interfacial layer. Because of this, the barrier height values of aged AI Ge contacts derived from I V and C V characteristics differ significantly. The dependence of the barrier height, (qSb) on the metal work function, q5m, for different metal germanium contacts shows that surface states play an important role in the formation of the barrier. The densit2, of germanium surface states is estimated to be D , - - 2 × lOl3eV ~cm 2. Surface charge and stress in the Si/SiO 2 system. S. D. BROTHERrON, T. G. READ, D. R. LAMa and A. F. W. WH3.OUGHBY. Solid St. Electron. 16, 1367 (1973). A model for the stress distribution in thermally oxidised silicon slices has been developed using beam theory and bimetallic strip theory. The stresses have been confirmed by making lattice parameter measurements on oxidised silicon using the APEX X-ray diffraction technique. The often suggested relationship between the surface charge density at the Si/SiO 2 interface and the stress in the silicon surface has
IC monostable SN74121 for easier detection of IR pulsed lasers. S. NEELAKANTAN and L. C. MANOHARAN. Int. J. Electron. 36, 279 (1974). A novel circuit using a digital IC monostable multivibrator for the detection of very narrow pulses using an ordinary oscilloscope is described in this research note.
Data processing, LSI will help to bring sight to the blind. Staff of The Neuroprostheses Program, University of Utah. Electronics 81 (24 Jan. 1974). Data from semiconductor camera in an artificial eye will be processed by circuitry held in spectacle frame, then transmitted to an array of electrodes implanted in a blind person's brain to evoke images.
CIRCUITS,
DEVICES
AND MATERIALS
been investigated and shown to be inconsistent. Finally, analysis of the variation of surface charge density with oxide thickness has caused us to postulate the presence of both positively and negatively charged centres at the interface. Effects of temperature on current instabilities caused by recombination centers in semiconductors. A R ELSHARKAWI and K. C. KAO. Solid St. Electron. 16, 1355 (1973). With the carrier distribution function approximated by a displaced Maxwellian function the current voltage characteristics for a semiconductor containing repulsive Coulomb recombination centers have been derived, and the current instabilities in n-GaAs as functions of temperature and applied field have been experimentally studied. The experimental results show that the threshold current for the onset of the current instabilities is not sensitive to temperature, but the corresponding threshold field decreases with increasing temperature; and that the current oscillation frequency increases and the amplitude decreases with increasing temperature. These results are in good agreement with the theory. Measuring semi-conductor properties of thermoelectric materials. D. J. RYDEN. Electronic Engng 59 (1974). An outline of the various measurements is given but the main purpose of this work is to describe those aspects which experience has shown to be a problem. A number of the points raised are not adequately covered in current text books on the subject. Redistribution and anisotropic diffusion of boron in (I00) and (111) oriented silicon. G. MASETTI, P. NEGRINI and S. SOLMI. Alta Frequenza XLII, 626 (Nov. 1973). The redistribution and the anisotropic diffusion of boron in ( I 11 ) and (100) oriented silicon have been experimentally studied at the temperature of 1100°C, in a large variety of oxidizing atmospheres and for times ranging from 15 min up to 9 hr. The boron diffused layers have been analyzed using a theoretical model, earlier presented by the authors, which correctly takes into account the redistribution phenomena at the oxide-silicon interface. In this way it has been demonstrated that the boron segregation coefficient is independent by the silicon orientation, and the anisotropic behaviour of boron diffusion in (100) silicon, only depends by the presence of oxygen within the drive-in atmosphere. These conclusions, together with the results of X-ray topography