Capacitancehyphen;voltage measurements of the dependence of flathyphen;band voltage of polycrystallinehyphen;silicon (polysilicon) gate metalhyphen;oxidehyphen;silicon capacitors on oxide thickness are used to measure the position of the Fermi level in degenerately doped polysilicon as a function of the doping of the polysilicon. For boronhyphen;doped polysilicon, the experimental difference between the Fermi level in polysilicon and the intrinsic level in the substrate silicon, fgr;ms, is sim;0.54 V. The Fermi level is pinned within 20 meV of the valence band edge. For arsenichyphen;doped and phosphorushyphen;doped polysilicon, evaluation of fgr;msis complicated by the occurrence of positive charge at the polysiliconhyphen;SiO2interface which is generated by reaction of doped polysilicon with SiO2. If such positive charge is close to the polysiliconhyphen;SiO2interface it acts as a dipole layer and lowers the values of fgr;ms. If positive charge is slightly deeper in the SiO2it contributes to negative bias instability due to electron injection into polysilicon capacitors. If electron exchange of positive charge with electrons in polysilicon does not occur, positive charge generated at the polysiliconhyphen;SiO2interface appears as fixed positive charge. For Ashyphen;doped polysilicon, fgr;mssim;minus;0.46 V; for Phyphen;doped polysilicon, fgr;mssim;minus;0.52 V. These experimental values of fgr;msare influenced by positive charge at the polysiliconhyphen;SiO2interface. We conclude that the Fermi level for degenerately doped nhyphen;type polysilicon is pinned close to but below the conduction band edge and does not depend on doping for carrier concentrations between 3times;1019and 4times;1020cmminus;3.
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