Query: Piezoresistance Effect in Germanium and Silicon

Candidate papers:

abstract: Uniaxial tension causes a change of resistivity in silicon and germanium of both $n$ and $p$ types. The complete tensor piezoresistance has been determined experimentally for these materials and expressed in terms of the pressure coefficient of resistivity and two simple shear coefficients. One of the shear coefficients for each of the materials is exceptionally large and cannot be explained in terms of previously known mechanisms. A possible microscopic mechanism proposed by C. Herring which could account for one large shear constant is discussed. This so called electron transfer effect arises in the structure of the energy bands of these semiconductors, and piezoresistance may therefore give important direct experimental information about this structure.
author_names: Charles S Smith
title: Piezoresistance Effect in Germanium and Silicon
year: 1954

abstract: The change of resistance in uniaxial compression has been measured for a number of single crystal specimens of high re resistivity $n$ and $p$ type germanium and silicon over the ranges 5\ifmmode^\circ\else\textdegree\fi{ to 350\ifmmode^\circ\else\textdegree\fi{}K (Ge) and 20\ifmmode^\circ\else\textdegree\fi{ to 350\ifmmode^\circ\else\textdegree\fi{}K (Si) For $n$ type material in the orientations giving the large effect\char22{[110] for $n$ Ge and [100] for $n$ Si\char22{}the piezoresistance is, as predicted by theory, linear in {T}\ensuremath{ }1} over most of the temperature range and with a small intercept. It is rather insensitive to impurity scattering. The departure from linearity in {T}\ensuremath{ }1} due to the onset of intervalley scattering near room temperature is estimated theoretically; it appears to be just barely detectable for $n$ Ge. The small piezoresistance of [100] oriented $n$ Ge varies little with temperature over most of the extrinsic range, again in accordance with theory. For $p$ Ge the results suggest that ideally pure material would show a piezo resistance dominated by a {T}\ensuremath{ }1} term for both [110] and [100] orientations. It is shown that this is to be expected theoretically, although the mechanism of piezoresistance for a degenerate band is more complicated than for a many valley model. However, the results for $p$ type material are, as they should be, much more sensitive to impurity scattering, even the sign of the effect varying with the purity for [100] specimens. For $p$ Si no simple temperature dependence is found, presumably because the spin orbit splitting of the bands is comparable with \mathrm{kT} At temperatures low enough to condense most of the carriers onto impurity centers, the piezoresistance departs from linearity in {T}\ensuremath{ }1} and varies from specimen to specimen. This behavior appears not to be due to impurity scattering; it may be caused in part by inhomogeneities. Surface conduction effects have been observed, but can be eliminated by etching. Neither Hall nor piezoresistance measurements reveal any detectable variation of the ionization energy of donors with strain. No departure of the piezoresistance from linearity in the applied stress has been observed.
author_names: F J Morin

Theodore H Geballe

Conyers Herring
title: Temperature Dependence of the Piezoresistance of High Purity Silicon and Germanium
year: 1957

abstract: Piezoresistive sensors are among the earliest micromachined silicon devices. The need for smaller, less expensive, higher performance sensors helped drive early micromachining technology, a precursor to microsystems or microelectromechanical systems (MEMS) The effect of stress on doped silicon and germanium has been known since the work of Smith at Bell Laboratories in 1954. Since then, researchers have extensively reported on microscale, piezoresistive strain gauges, pressure sensors, accelerometers, and cantilever force/displacement sensors, including many commercially successful devices. In this paper, we review the history of piezoresistance, its physics and related fabrication techniques. We also discuss electrical noise in piezoresistors, device examples and design considerations, and alternative materials. This paper provides a comprehensive overview of integrated piezoresistor technology with an introduction to the physics of piezoresistivity, process and material selection and design guidance useful to researchers and device engineers.
author_names: A Alvin Barlian

Woo-Tae Park

Joseph R Mallon

Ali J Rastegar

Beth L Pruitt
title: Review: Semiconductor Piezoresistance for Microsystems
venue: Proceedings of the IEEE
year: 2009

abstract: A high sensitivity silicon germanium accelerometer based on meso piezoresistance effect is proposed in this letter,we took Si1 xGex/Si film as core component,and deviced double cantilever beamwith structure piezoresistive silicon germanium acceleration sensor.The influence of adscititious stress on the sensitivity are analyzed by theoretic analysis and emulational calculation,based on it,we can draw the conclution that sensitivity of piezoresistive silicon micro acceleration sensor are increased one number lever.The perference to the optimization of the stucture is provided.
author_names: Wen Ting-dun
title: Study on Meso Piezoresistive Type Silicon Germanium Accelerometer
year: 2009

abstract: Abstract The large piezoresistance effect in a Ge 0 04 Si alloy has been measured and found to be proportional to T 1 between 77degK and 300degK and to be 15 per cent greater than in pure Ge. Various origins for this difference are examined, and, using some evidence from the elastogalvanomagnetic effects, it is concluded that at least part of the difference is due to intervalley scattering of the alloy type in the alloy.
author_names: Robert W Keyes
title: Elastoresistance effects in a germanium silicon alloy
year: 1957

abstract: Abstract A modification of the Haynes Shockley technique has been developed to permit measurement of minority carrier mobility independent of sample geometry or lifetime. Electron mobility and piezoresistance was measured as a function of uniaxial stress up to 7 x 109 dyne/cm2. The mobility data was fitted to a theory incorporating the effects of stress on intervalley scattering. A current pinch effect was observed in intrinsic germanium and related to theory. A theory for pinch effect under illumination and with two lifetime regions was developed. Recently reported observations of the Gunn effect in silicon and germanium are reviewed relative to theoretical predictions made earlier by the present authors. Implications of the stress dependence of electron mobility on device design are discussed. (Author)
author_names: Michael W Cresswell

Daniel R Muss
title: UNIAXIAL STRESS IN SILICON AND GERMANIUM. VOLUME I. SECTIONS 1 AND 2.
year: 1968

abstract: Piezoresistive sensors are among the earliest micromachined silicon devices. The need for smaller, less expensive, higher performance sensors helped drive early micromachining technology, a precursor to microsystems or microelectromechanical systems (MEMS) The effect of stress on doped silicon and germanium has been known since the work of Smith at Bell Laboratories in 1954. Since then, researchers have extensively reported on microscale, piezo resistive strain gauges, pressure sensors, accelerometers, and cantilever force/displacement sensors, including many com mercially successful devices. In this paper, we review the history of piezoresistance, its physics and related fabrication techniques. We also discuss electrical noise in piezoresistors, device examples and design considerations, and alternative materials. This paper provides a comprehensive overview of integrated piezoresistor technology with an introduction to the physics of piezoresistivity, process and material selection and design guidance useful to researchers and device engineers.
author_names: A Alvin Barlian

J R Mallon

Ali J Rastegar

Beth L Pruitt
title: Review: Semiconductor Piezoresistance for
year: 2009

abstract: The plezoreslstance tensor components for n type Mg2Sn have been measured from $0 to 300degK. The piezoreslstance effect in Mg2Sn Is larger than the piezoreslstance effect in germanium or silicon. Prom these measurements and the elastic constants of Davis et. ai the elastoresistance tensor compon ents were obtained and found to satisfy m]_]_ (r)ll large and m^.2^ small, in the temperature range 50 to 200degK. These relationships confirm that n type Hg2Sn is a many valley semi conductor with constant energy ellipsoids in the direc tion. The fact that mi% and mi2 were both linear in the temperature range 6o 175degK indicates that inter valley scat tering is unimportant in the extrinsic temperature region. The small value of the volume coefficient, (mn 2m2_2)/3. indicates that carrier mobility in n type Ng2Sn is relatively insensitive to changes in sample volume. The deformation potential was determined from a combination of these piezore slstance results and Umeda's magnetoresistance data and found to satisfy the relation Hdeg(1+(r)T) where= 10.1 ev and ot 4.3 0.6) X 10" High stress piezoreslstance measurements yielded a deformation potential of 8^ =18 ev and mobility anlsotropy of K= 2.65 at 77.4degK. Umeda obtained K 3.51. A possible qualitative explanation of these differences can be given in terms of a change with stress of the position of the donor levels with respect to the conduction band.
author_names: Leon Duane Crossman
title: Piezoresistance of N Type Magnesium Stannide.
year: 1967

abstract: We have simulated the piezoresistance coefficients (Pie Coefficients) in some certain Germanium nanowire (GeNW) Silicon nanowire (SiNW) and several Ge/Si core/shell nanowires based on the first principles calculations. All the nanowires are with a same diameter in ;111> direction and remain unsaturated on surface. In these ;111> nanowires, It was found that the Pie Coefficients of the SiNW and the Ge<sub>1</sub>Si<sub>3</sub> (Ge/Si core/shell nanowire with three layers of silicon atoms) can reach as much as 35.26 x 10<sup> 11</sup>Pa<sup> 1</sup> and 30.0 x 10<sup> 11</sup>Pa<sup> 1</sup> under 2.5% tension in the longitudinal direction. And all those of the GeNW and the Ge<sub>3</sub>Si<sub>1</sub> (with only one silicon atom layer) almost kept negative values from 1 x 10<sup> 11</sup> Pa<sup> 1</sup> to 9 x 10<sup> 11</sup> Pa<sup> 1</sup> whether under compressions or tensions. However, under compressions, the Ge<sub>2</sub>Si<sub>2</sub> (with two layers of silicon atoms surrounded outside) almost had no piezoresistive effect.
author_names: Lei Li

ShuangYing Lei

Hong Yu

Qing-An Huang
title: First principles study on the piezoresistive effect of Ge/Si core/shell Nanowires
venue: 2012 IEEE Sensors
year: 2012

abstract: Schottky diodes utilized for mechanical stress effect studies were fabricated using aluminum contacts to polycrystalline diamond thin films grown by a hot filament assisted chemical vapor deposition process. Compressive stress was found to have a large effect on the forward biased current voltage characteristics of the diode, whereas the effect on the reverse biased characteristics was relatively small. This stress effect on the forward biased diamond Schottky diode was attributed to piezojunction and piezoresistance effects that dominated the diode current voltage characteristics in the small and large bias regions, respectively. At a large constant forward bias current, a good linear relationship between output voltage and applied force was observed for force of less than 10 N, as predicted by the piezoresistance effect. The measured force sensitivity of the diode was as high as 0.75 V/N at 1 mA forward bias. Compared to either silicon or germanium junction diodes and tunnel diodes, polycrystalline diam.
author_names: G Zhao

E M Charlson

E J Charlson

T Stacy

Jon M Meese

Galina Popovici

Mark Antonio Prelas
title: Effect of mechanical stress on current voltage characteristics of thin film polycrystalline diamond Schottky diodes
year: 1993