STRESS-DEPENDENT HOLE EFFECTIVE MASSES AND PIEZORESISTIVE PROPERTIES OF P-TYPE MONOCRYSTALLINE AND POLYCRYSTALLINE SILICON

Piezoresistive effects of p-type polycrystalline silicon underline tha t longitudinal and transversal piezoresistive properties in monocrysta lline silicon do not have the same physical origin, which is not accou nted for in current models. This difference is highlighted by the stud y of the mechanical stress effect on the valence band, which shows tha t piezoresistive properties of p-type monocrystalline silicon can he e xplained in terms of both hole transfer between heavy-and light-hole v alence bands and stress-dependent hole effective masses. The quantific ation of these phenomena points out that longitudinal piezoresistive p roperties are mainly due to the hole transfer, whereas transversal one s an mainly attributed to the effective mass change effects. This enab les one to model p-type polycrystalline silicon piezoresistivity, in p articular the sign change of the transversal gauge factor at high dopi ng level. [S0163-1829(98)01615-4].