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The piezoelectronic transistor:A nanoactuator-based post-CMOS digital switch with high speed and low power

Class: Bio MEMS Components and SystemTeacher ： Professor Hsu

Name: Po Yuan ChengID: MA0R0204

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Outline

• Abstract

• Transistor

• Principles of PET operation

• Simulation and modeling of PET performance

• Summary and conclusion

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Abstract

Moore’s law of transistor scaling, the exponential increase in the number of complementary metal oxide semiconductor (CMOS) transistors per unit area, continues unabated.

The development of a new digital switch,the piezoelectronic transistor (PET), is designed to circumvent the speed and power limitations of the CMOS transistor.

The PET functions by transducing an electrical gate signal into acoustic form via a high performance relaxor piezoelectric (PE) element. The acoustic signal then compresses a rare-earth chalcogenide intermediate valence piezoresistive (PR) element, which undergoes an insulator-to metal transition driven by f-electron physics.

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Transistor

The transistor is a solid state device components, it has the advantages of small size, high efficiency, long life and fast.

The current flowing into the transistor current is equal to the outflow transistor.

IE = IB+ IC

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Piezoelectrics effectDirect piezoelectric effectThe piezoelectric material when subjected to physical stress, the material body of the electric dipole moment due to the compression becomes short, the piezoelectric material to resist this change will produce the same amount of positive and negative charge on the surface of the material opposite to intact .

Converes piezoelectric effectWhen the electric field (voltage) is applied to the surface of the piezoelectric material, the electric dipole moment in the electric field will be elongated, the piezoelectric material to resist changes will be elongated along the direction of the electric field.

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Piezoresistive effect

• The piezoresistive effect is used to describe the change in resistance of the material subjected to mechanical stress.

• Unlike the piezoelectric effect, the piezoresistive effect only produce a change in impedance does not charge-generating.

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Principles of PET operation

Expansion of the PE element results in compression of the adjacent piezoresistive element. For this to occur, the whole PET stack needs to be vertically clamped within a rigid structure made of a high yield material (HYM), sketched in semi-transparent form in Figure 1a .

The aspect ratio of the PR is plate-like (see Figure 1a ), its thickness vertically being less than its width. This facilitates transmission of current in the vertical direction, lowering the electrical resistance.

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SmSe The high piezoresistive response of rare-earth intermediate valence chalcogenide compounds such as SmSe and Smx m Eu 1–x S arises as follows (see Figure 2 a).

In these materials, there is an empty 5d conduction band, an occupied 4p valence band, and in the bandgap a narrow, occupied, 4f band derived from the j = 5/2 4f subshell. Under pressure (see Figure 2b ), the energy gap E g between the filed 4f band and the empty 5d conduction band narrows, allowing the 4f electrons to be thermally promoted into the 5d conduction band.

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Simulation and modeling(1/1) A very simple piezoelectric logic circuit is the inverter; Figure 4a shows a chain of three inverters.

With the input low (at ground, zero, potential), the lower PET is off, the upper PET on, then the output is high (at the line voltage V DD ). With the input high, the upper PET is off, the lower PET is on, and the output is low. Changing the input from low to high changes the output from high to lowIn Figure 4b , we show the results of the simulation of a chain of nine PET inverters. For each geometry, lower voltage operation leads to lower operating frequency, f (as in CMOS).

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Simulation and modeling(1/2)

• However, at line voltages between 0.1 V and 0.2 V, PETs are capable of sustaining multi-GHz clock speeds—this is not achievable with CMOS, where line voltages V DD below about 1 V lead to a dramatic slowing down/an inadequate ON/OFF ratio.

• These simulations show that satisfaction of the desired engineering goal of low power combined with high speed by piezoelectronics is within sight.

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Summary and conclusion(1/1)• The challenge to the information technology (IT)

industry posed by the end of complementary metal oxide semiconductor (CMOS) voltage scaling in 2003, resulting in freezing of processor clock speed, can only be met by a computer switching device based on a novel principle.

• The piezoelectronic transistor (PET) computer switch that we have proposed is found by modeling and simulation to have an adequate ON/OFF ratio, significant gain, and high speed both in terms of the sound transmission time and the resistance-capacitance (RC) time.

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Summary and conclusion(1/2)

• Simulations based on properties of known materials show that the device can operate at very low voltages on the order of 0.1 V at very high multi-GHz clock speeds.

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• Thank you for your attention