- Email: [email protected]
Effective masses in (100) silicon inversion layers
World Abstracts on Microelectronics and Reliability 557 'i in doped and undoped amorphous silicon. We also report and anig0tropic conductivity measurements proved a comthe observation of equilibrium surface or interface spin plete transfer of electrons from isotropic into anisotropic densities ~ 10la cm-2 and volume spin densities valleys. The existence of domains is necessary for the ~ 6 x 1015 cm -a. The small number of spins observed in explanation of the experimental results. equilibrium compared to the large optically induced spin Microwave hot electron effects in semiconductor quantized density shows that most electrons are spin paired in equiinversion layers. D. K. FERRY and P. DAS. Solid-St. Eleclibrium. We conclude that this implies a very small mean tron. 20, 355 (1977). Hot electron microwave conductivity effective correlation energy, U ~ kT. of quantized inversion layers in semiconductor surfaces has Electron states at steps in semiconductor surfaces. 1~. LouIs been calculated based on a displaced Maxwellian approxiand FELIX YNDURAIN. Solid St. Commun. 22, 147 (1977). marion for the electron distribution function. The calculaBased on the Bethe-Peierls approximation we have devel- tions performed take into account repopularion of carriers oped a method to study surfaces where local deviations among the various subbands. The effects of the energy, from periodicity are present. Since the method leaves out momentum and intervalley population exchange rates due everything but short-range order, the effect of particular to scattering by acoustical and intervalley phonons are inlocal configurations are easily studied. In particular, we cluded in the derivations. The results are applied to silicon apply the method to study the electronic structure of steps where the electron energy and momentum losses by interin Si surfaces. The results are in fair agreement with pho- valley phonons in both the zero-order coupled and firstorder coupled cases are important. Numerical computoemission experimental data. tations for the microwave conductivity of silicon are presEffective masses in (100) silicon inversion layers. I. EISELE, ented as a function of bias electric field and frequency. H. GESCH and G. DORDA. Solid St. Commun. 22, 185 (1977). It is found that significant changes in the conductivity conShubnikov--de Haas oscillations at low electron concen- tribution for a fixed bias field occur at frequencies on the trations have been studied under mechanical stress. The order of the intervalley repopulation rate. Though no exeffective cyclotron mass of the anisotropic valleys has been perimental work in this frequency range has been perdetermined to be mc/m o = 0.43. Additional piezoresistance formed, it should be easily observable.
8. THICK- AND THIN-FILM COMPONENTS, HYBRID CIRCUITS AND MATERIALS Thin film resistor networks in hybrid circuits, LEONHARD stress to use as a screening procedure for solder leaching. GROTH. Solid St. Technol. p. 45 (March 1977). The use Guidelines are presented for performing the screening test of thin film precision resistor networks is increasing in and determining a rating for any material combination. thick film hybrids, where their tighter tolerances, lower TCR, better TCR tracking and small size make possible The effect of film thickness on certain properties of Cr-SiO better performance at higher packaging densities. This cermet thin films. Electron. Technol. 10, (1) 117 (1977). article discusses the advantages and disadvantages of thin Results are discussed of the investigations of the effect of film chip networks. Aspects of hybrid design with chip film thickness on density, resistivity, sheet resistivity and networks and chip design are outlined. Several hybrid con- adhesion of the cermet thin films (50%-Cr, 50%-SIO comverters and an active filter are discussed to illustrate the position) as well as of this effect on annealing coefficient and temperature coefficient of resistance of resistors manuthick film/thin film hybrid combination. factured from these films. Screening procedure for adhesion degradation due to solder The investigations were performed in the thickness range leaching in thick-film hybrid ngcrocircu~ts. STEPHEN S. from about 180A to about 1430A. LEVER. Solid St. Technol. p. 39 (March 1977). The results of an experiment to determine practical screening and qua- Advances in film extend component capabilities. LUCINDA lity assurance procedures to preclude excessive adhesion MATTERA. Electronics p. 114 (May 12, 1977). The rise of degradation, due to solder leaching, in gold alloy/solder thick and thin films has changed the components landsystems in thick-film hybrid microcircuits are described. scape irrevocably. Like semiconductors, passive comThese results include a comparative rating among the ponents are no longer single devices but often complex materials tested, along with criteria for rating different networks of both elements and interconnects. Moreover, materials. Four environmental stresses were compared to most of the new developments in components are tied to determine which one to use as a quality assurance test improvements in films and production techniques--so for adhesion decay. The test method consisted of soldering closely tied that it is becoming increasingly difficult to sepcopper pins to conductor pads on the substrate, and then arate the two. pull-testing the pins to the destruction of the conductor/ substrate bonds, both before and after environmental Electrical properties of CdxHgt _xTe thin films for hall stresses. This method provides a measurement of both ten- effect device applications. ANNA PIOTROWSKA. Electron. sile adhesion between the soldered conductor and the sub- Technol. 9, (3/4) 83 (1976). The paper presents the results strate, and adhesion degradation promoted by the environ- of investigations of the structure and electrical properties mental stress. Seven thick-film conductor materials and of vacuum deposited CdxHgl _xTe thin films of a composithree solder compositions were used, making a total of tion 0 < x < 0.22 and a thickness d = 0.5-12/an. 21 conductor/solder systems tested. Pins were soldered to The degree of structural order has been analysed, the each of the seven conductor materials with each of the existence of various phases of the chemical composition three solders. Adhesion measurements were made immedi- has been established, the lattice constant and the size of ately, again after a minimum three-day shelf life, and also crystalline grains have been determined. after each environmental stress. The median force-per-unit The effect of chemical composition and film thickness area values for each conductor/solder/environmental stress upon the electrical properties of the film have been anacombination were tabulated and plotted. The results are • lysed. presented to show the relative degradations of the different A comparison has been made between the properties materials. Based on the results of the experiment, the tem- of thin film and bulk material and the reasons of differperature cycling stress appears to be the most practical ences between these properties have been established.
8. THICK- AND THIN-FILM COMPONENTS, HYBRID CIRCUITS AND MATERIALS Thin film resistor networks in hybrid circuits, LEONHARD stress to use as a screening procedure for solder leaching. GROTH. Solid St. Technol. p. 45 (March 1977). The use Guidelines are presented for performing the screening test of thin film precision resistor networks is increasing in and determining a rating for any material combination. thick film hybrids, where their tighter tolerances, lower TCR, better TCR tracking and small size make possible The effect of film thickness on certain properties of Cr-SiO better performance at higher packaging densities. This cermet thin films. Electron. Technol. 10, (1) 117 (1977). article discusses the advantages and disadvantages of thin Results are discussed of the investigations of the effect of film chip networks. Aspects of hybrid design with chip film thickness on density, resistivity, sheet resistivity and networks and chip design are outlined. Several hybrid con- adhesion of the cermet thin films (50%-Cr, 50%-SIO comverters and an active filter are discussed to illustrate the position) as well as of this effect on annealing coefficient and temperature coefficient of resistance of resistors manuthick film/thin film hybrid combination. factured from these films. Screening procedure for adhesion degradation due to solder The investigations were performed in the thickness range leaching in thick-film hybrid ngcrocircu~ts. STEPHEN S. from about 180A to about 1430A. LEVER. Solid St. Technol. p. 39 (March 1977). The results of an experiment to determine practical screening and qua- Advances in film extend component capabilities. LUCINDA lity assurance procedures to preclude excessive adhesion MATTERA. Electronics p. 114 (May 12, 1977). The rise of degradation, due to solder leaching, in gold alloy/solder thick and thin films has changed the components landsystems in thick-film hybrid microcircuits are described. scape irrevocably. Like semiconductors, passive comThese results include a comparative rating among the ponents are no longer single devices but often complex materials tested, along with criteria for rating different networks of both elements and interconnects. Moreover, materials. Four environmental stresses were compared to most of the new developments in components are tied to determine which one to use as a quality assurance test improvements in films and production techniques--so for adhesion decay. The test method consisted of soldering closely tied that it is becoming increasingly difficult to sepcopper pins to conductor pads on the substrate, and then arate the two. pull-testing the pins to the destruction of the conductor/ substrate bonds, both before and after environmental Electrical properties of CdxHgt _xTe thin films for hall stresses. This method provides a measurement of both ten- effect device applications. ANNA PIOTROWSKA. Electron. sile adhesion between the soldered conductor and the sub- Technol. 9, (3/4) 83 (1976). The paper presents the results strate, and adhesion degradation promoted by the environ- of investigations of the structure and electrical properties mental stress. Seven thick-film conductor materials and of vacuum deposited CdxHgl _xTe thin films of a composithree solder compositions were used, making a total of tion 0 < x < 0.22 and a thickness d = 0.5-12/an. 21 conductor/solder systems tested. Pins were soldered to The degree of structural order has been analysed, the each of the seven conductor materials with each of the existence of various phases of the chemical composition three solders. Adhesion measurements were made immedi- has been established, the lattice constant and the size of ately, again after a minimum three-day shelf life, and also crystalline grains have been determined. after each environmental stress. The median force-per-unit The effect of chemical composition and film thickness area values for each conductor/solder/environmental stress upon the electrical properties of the film have been anacombination were tabulated and plotted. The results are • lysed. presented to show the relative degradations of the different A comparison has been made between the properties materials. Based on the results of the experiment, the tem- of thin film and bulk material and the reasons of differperature cycling stress appears to be the most practical ences between these properties have been established.