Stress-dependent hole effective masses and piezoresistive properties ofp-type monocrystalline and polycrystalline silicon

Abstract

Piezoresistive effects of p-type polycrystalline silicon underline that longitudinal and transversal piezoresistive properties in monocrystalline silicon do not have the same physical origin, which is not accounted for in current models. This difference is highlighted by the study of the mechanical stress effect on the valence band, which shows that piezoresistive properties of p-type monocrystalline silicon can be explained in terms of both hole transfer between heavy-and light-hole valence bands and stress-dependent hole effective masses. The quantification of these phenomena points out that longitudinal piezoresistive properties are mainly due to the hole transfer, whereas transversal ones are mainly attributed to the effective mass change effects. This enables one to model p-type polycrystalline silicon piezoresistivity, in particular the sign change of the transversal gauge factor at high doping level. ͓S0163-1829͑98͒01615-4͔

Piezoresistance in p-type silicon revisited

“…9 Recently, Kozlovskiy et al 10 carried out a detailed analytical study of piezoresistance in p-type silicon using analytical valence band models of varying complexity, derived from Pikus and Bir, 11 combined with a power law model for momentum relaxation time, as was also used in previous works. [12][13][14] Approximations to the valence band structure valid close to the top of the valence band were used in Refs. 13 and 14, while Toriyama and Sugiyama 12 used an approximation valid at larger hole energies.…”

An alternative approach to exact wave functions for time-dependent coupled oscillator model of charged particle in variable magnetic field

“…The effective mass of charged particles, such as electrons or holes in any system, may modified through their interaction with surroundings or various excitations like energy [40], stress [41], temperature [42], and pressure [43]. It is therefore natural to think that the effective mass varies with time according to the change of the environments.…”

Fabrication, Metrology and Modeling of Protective Coatings on Metallic MEMS Components

“…In semiconductor Si gages and other materials with degenerate hole bands, strain breaks the degeneracy and leads to changes in the proportion of heavy and light holes as well as in the effective masses themselves. This is the reason that Si strain gages are consistently made of p-type material [15].…”

“…By comparison, the strain sensitivities of semiconductor silicon strain gages are typically in the range 5 to 175 [13], while those of metal foil sensors are positive and typically in the range from about 2 up to approximately 6 [14]. The origin of piezoresistivity in crystalline semiconductors such as Ge and Si has been discussed by various authors [15]. However, in ITO the mechanism is unknown.…”