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Effect of stress on the carrier generation rate in gold-doped silicon
WORLD
ABSTRACTS
ON MICROELECTRONICS
idealized surfaces of diamond and zinc blended types of semiconductor. O n the diamond type semiconductors a eontimmus blend of surface states can hold two e l e c ~ n s per surface atom and is half filled, pegging the Fermi level about one-third of the way up the band gap. I n zinc blend type materials the band is split into two, with a b a n d gap between t h e m depending o n the degree of ionicity. T h e theory can be extended to metel-to-semiconductor junctions and oxide-to-semiconductor interfaces. I n the latter case there are n o intrirmic surface states, and some remarks will be made about localized states centred on impurities or defects.
Effect of stt~m o n t h e c a r r i e r g o n e r a e l o n r a t e i n g o l d - d o p e d s i l i c o n . J. L. Pax~cs, J. J. Wos'rM~-~, L. K. MON~STH end J. R. HAumm, Solid-State Electron. 13 (1970), p. 1519. T h e thermal generation rate of charge carriers in a depletion region in gold-doped silicon was measured as a function of strain applied in the [101] direction over a range of temperatures. T h e r m a l generation rate was also measured as a function of [100] strain at a single temperature. Relaxation to equilibrium of a deeply depicted metal--oxide--semiconductor capacitor was used to measure generation rate. T h e generation rate was observed to increase nearly 100 per cent from zero applied strain to a n applied strain of 5 X 10"s, at --20°C. Experimental results were explained using a model based on Shockley-Read statistics and results from deformation-potential theory. Agreement between theory and experiment was obtained u n d e r the condition that the gold impurity energy level split with applied strain and the centre of gravity of the two levels shifted upward with a hydrostatic coefficient. T h e increase in generation rate was in excess of that caused by bend extrema shifts only. U n t o r s u c h u n g g e s p u t t e r t e r S i O . 4 c l d c h t e n a u f Sie i n k r i s m l l e n . K. 17dnm>L and D. WIDMANN,SolidState Electron. 13 (1970), p. 1445. (In German.) SiOa layers sputtered directly on silicon wafers are tending to trap instability. O n the other hand, ion instability does not seem to play an important role. T h e r e is a lower pinhole density in sputtered SiOs films than in thermally grown SiOz alms of equal thickness. T h e dielectric strength as well as the etching rate in buffered fluoric acid are equal to those of thermally grown SiOi.
A d e t ~ l z d ~ n a l y ~ o f t h r e e - l e v e l e l e c t r o n tramffer. C. Hzt~UM and H. D. Rm~, Proc. lOth Into~national Conf. on the Physics of Semiconductors (CONF-700801). Massachusetts Institute of Technology, Cambridge, Mass., USA, 17-21 August (1970). Electron transfer between three appropriately coupled sets of conduct/on band velleys produces transport properties peculiarly favourable for transferred electron devices. A theoretical study has been made of the compounds and mixed crystals which should show these effects. T h e paper is in two parts. T h e first reports M o n t e Carlo calculations for those compositions within the I n P - I n A s and InSb-G a S b systems which have the appropriate band structure. T h e velocity-field characteristic shows a region of
AND
RELIABILITY
149
large negative differential mobility followed by a region of low positive differential mobility. T h e peak-to-valley ratio is higher than in two-level systems such as GaPs. T h e second part is an analysis of the further comequancea of three-level transfer. It includea device simulations. T h e results indicate that domain formation is inhibited, and other modea of operation are inherently favoured. I n this way the full negative reaistanea can b e exploited more ~_/ly than in GaAJ. A brief mention is made of experimental reaults which confirm the theoretical predictions. Selection of thermocouplm for temperatura proflU,,o o f s e m i c o n d u c t o r d i f f m i o n / h m a c e s . I. O. NiffJoN, Solid-State T~knol., October (1970), p. 33. Dcterraining the pm__oe~__temperatures in semiconductor di/fimlon furnaces is, at best, a relatively inaccurate procedure when compared with precision electrical measurements. I n profile measurements uncertainties in thermocouple measuring systems can create errors which lead to coetly losses in product yield. Preventing these errors and losses requires proper selection of thermocouple materials, care in assembly and observance of proper measurement techniques. I n this article factors contributing to thermocouple uncertainties, criteria for wire selection, a method of assembling a profiling thermocouple, end techniques using various thermocouple measuring systems are discussed.
Photomodulatlon of the photoemissive yield near t h r e s h o l d i n s i l l c o a . J. E. Rowe, Proc. 10th International Conf. on the Physics of Semiconduct~'s ( C O N F 700801). Massachusetts Institute of Technology, Cambridge, Mass., USA, 17-21 August (1970). Photomodulation of the room-temperature photoemissive yield of vacuum cleaved ( I I I ) silicon surfaces was investigated for u.v. energies near threshold using a 0"7 m W H e - N e laser as a secondary light beam. T h e --A'9 eV laser photons cause an increase in yield by decreasing the band bending which is due to surface states. T h e photomodulated yield, A Y / Y , gives a sensitive measurement of threshold energies, and a broadened (E-Et) -z lineshape is observed at E, ~ 4"94 -I- 0"03 eV. A second, weaker threshold at Et" ~ 5"07 ~0-03 eV is observed for the first time and is interpreted as a surface band critical point. Assuming that these critical points are the extrerna of the occupied surface band, a band width of 0"13 eV is obtained. T h i s is less than the upper limit of 0-2 eV dctermined by Allen and Gobelil from the bulk doping dependence of photoemission.
Interface
states
in metal-oxlde-semicemductor
f i e l d - e f f e c t t r a n s i s t o r s . C. Sequit~ and E. BALDn~OSS, Sol, J-State Electron. 13 (1970), p. 1527. The effect of 6°Co-~-radiation on M O S field-effect transistors manifeats itself as a shift of the characteristics, a decrease in the transconductance and the appearance of long-time instabilities. I n this paper the results of an investigation of the instabilities produced by charge exchange associated with states near the oxide-silicon interface are
ABSTRACTS
ON MICROELECTRONICS
idealized surfaces of diamond and zinc blended types of semiconductor. O n the diamond type semiconductors a eontimmus blend of surface states can hold two e l e c ~ n s per surface atom and is half filled, pegging the Fermi level about one-third of the way up the band gap. I n zinc blend type materials the band is split into two, with a b a n d gap between t h e m depending o n the degree of ionicity. T h e theory can be extended to metel-to-semiconductor junctions and oxide-to-semiconductor interfaces. I n the latter case there are n o intrirmic surface states, and some remarks will be made about localized states centred on impurities or defects.
Effect of stt~m o n t h e c a r r i e r g o n e r a e l o n r a t e i n g o l d - d o p e d s i l i c o n . J. L. Pax~cs, J. J. Wos'rM~-~, L. K. MON~STH end J. R. HAumm, Solid-State Electron. 13 (1970), p. 1519. T h e thermal generation rate of charge carriers in a depletion region in gold-doped silicon was measured as a function of strain applied in the [101] direction over a range of temperatures. T h e r m a l generation rate was also measured as a function of [100] strain at a single temperature. Relaxation to equilibrium of a deeply depicted metal--oxide--semiconductor capacitor was used to measure generation rate. T h e generation rate was observed to increase nearly 100 per cent from zero applied strain to a n applied strain of 5 X 10"s, at --20°C. Experimental results were explained using a model based on Shockley-Read statistics and results from deformation-potential theory. Agreement between theory and experiment was obtained u n d e r the condition that the gold impurity energy level split with applied strain and the centre of gravity of the two levels shifted upward with a hydrostatic coefficient. T h e increase in generation rate was in excess of that caused by bend extrema shifts only. U n t o r s u c h u n g g e s p u t t e r t e r S i O . 4 c l d c h t e n a u f Sie i n k r i s m l l e n . K. 17dnm>L and D. WIDMANN,SolidState Electron. 13 (1970), p. 1445. (In German.) SiOa layers sputtered directly on silicon wafers are tending to trap instability. O n the other hand, ion instability does not seem to play an important role. T h e r e is a lower pinhole density in sputtered SiOs films than in thermally grown SiOz alms of equal thickness. T h e dielectric strength as well as the etching rate in buffered fluoric acid are equal to those of thermally grown SiOi.
A d e t ~ l z d ~ n a l y ~ o f t h r e e - l e v e l e l e c t r o n tramffer. C. Hzt~UM and H. D. Rm~, Proc. lOth Into~national Conf. on the Physics of Semiconductors (CONF-700801). Massachusetts Institute of Technology, Cambridge, Mass., USA, 17-21 August (1970). Electron transfer between three appropriately coupled sets of conduct/on band velleys produces transport properties peculiarly favourable for transferred electron devices. A theoretical study has been made of the compounds and mixed crystals which should show these effects. T h e paper is in two parts. T h e first reports M o n t e Carlo calculations for those compositions within the I n P - I n A s and InSb-G a S b systems which have the appropriate band structure. T h e velocity-field characteristic shows a region of
AND
RELIABILITY
149
large negative differential mobility followed by a region of low positive differential mobility. T h e peak-to-valley ratio is higher than in two-level systems such as GaPs. T h e second part is an analysis of the further comequancea of three-level transfer. It includea device simulations. T h e results indicate that domain formation is inhibited, and other modea of operation are inherently favoured. I n this way the full negative reaistanea can b e exploited more ~_/ly than in GaAJ. A brief mention is made of experimental reaults which confirm the theoretical predictions. Selection of thermocouplm for temperatura proflU,,o o f s e m i c o n d u c t o r d i f f m i o n / h m a c e s . I. O. NiffJoN, Solid-State T~knol., October (1970), p. 33. Dcterraining the pm__oe~__temperatures in semiconductor di/fimlon furnaces is, at best, a relatively inaccurate procedure when compared with precision electrical measurements. I n profile measurements uncertainties in thermocouple measuring systems can create errors which lead to coetly losses in product yield. Preventing these errors and losses requires proper selection of thermocouple materials, care in assembly and observance of proper measurement techniques. I n this article factors contributing to thermocouple uncertainties, criteria for wire selection, a method of assembling a profiling thermocouple, end techniques using various thermocouple measuring systems are discussed.
Photomodulatlon of the photoemissive yield near t h r e s h o l d i n s i l l c o a . J. E. Rowe, Proc. 10th International Conf. on the Physics of Semiconduct~'s ( C O N F 700801). Massachusetts Institute of Technology, Cambridge, Mass., USA, 17-21 August (1970). Photomodulation of the room-temperature photoemissive yield of vacuum cleaved ( I I I ) silicon surfaces was investigated for u.v. energies near threshold using a 0"7 m W H e - N e laser as a secondary light beam. T h e --A'9 eV laser photons cause an increase in yield by decreasing the band bending which is due to surface states. T h e photomodulated yield, A Y / Y , gives a sensitive measurement of threshold energies, and a broadened (E-Et) -z lineshape is observed at E, ~ 4"94 -I- 0"03 eV. A second, weaker threshold at Et" ~ 5"07 ~0-03 eV is observed for the first time and is interpreted as a surface band critical point. Assuming that these critical points are the extrerna of the occupied surface band, a band width of 0"13 eV is obtained. T h i s is less than the upper limit of 0-2 eV dctermined by Allen and Gobelil from the bulk doping dependence of photoemission.
Interface
states
in metal-oxlde-semicemductor
f i e l d - e f f e c t t r a n s i s t o r s . C. Sequit~ and E. BALDn~OSS, Sol, J-State Electron. 13 (1970), p. 1527. The effect of 6°Co-~-radiation on M O S field-effect transistors manifeats itself as a shift of the characteristics, a decrease in the transconductance and the appearance of long-time instabilities. I n this paper the results of an investigation of the instabilities produced by charge exchange associated with states near the oxide-silicon interface are