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Poly Depletion
Polysilicon depletion effect is the phenomenon in which unwanted variation of threshold voltage of the MOSFET devices using polysilicon as gate material is observed, leading to unpredicted behavior of the electronic circuit. Because of this variation High-κ dielectric, High-k Dielectric Metal Gates (HKMG) were introduced to solve the issue. Polycrystalline silicon, also called polysilicon, is a material consisting of small silicon crystals. The latter differs from Crystalline silicon, monocrystalline silicon used for Semiconductor device, semiconductor electronics and solar cells, and from amorphous silicon, used for thin film devices and solar cells. Gate material choice The gate contact may be of polysilicon or metal, previously polysilicon was chosen over metal because the interfacing between polysilicon and gate oxide (Silicon dioxide, SiO2) was favorable. But the conductivity of the poly-silicon layer is very low and because of this low conductivity, the charge accumulation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Threshold Voltage
The threshold voltage, commonly abbreviated as Vth or VGS(th), of a field-effect transistor (FET) is the minimum gate-to-source voltage (VGS) that is needed to create a conducting path between the source and drain terminals. It is an important scaling factor to maintain power efficiency. When referring to a junction field-effect transistor (JFET), the threshold voltage is often called pinch-off voltage instead. This is somewhat confusing since ''pinch off'' applied to insulated-gate field-effect transistor (IGFET) refers to the channel pinching that leads to current saturation behavior under high source–drain bias, even though the current is never off. Unlike ''pinch off'', the term ''threshold voltage'' is unambiguous and refers to the same concept in any field-effect transistor. Basic principles In n-channel ''enhancement-mode'' devices, a conductive channel does not exist naturally within the transistor. With no VGS, dopant ions added to the body of the FET form a region ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
