Method for measuring differential capacitance of ferroelectric film by rapid voltage sweep

A technology of ferroelectric thin film and differential capacitance, which is applied in the direction of measuring resistance/reactance/impedance, measuring electrical variables, measuring devices, etc., can solve the problem that the dielectric properties cannot be measured, and the microscopic physical mechanism of the dielectric properties of ferroelectric film capacitors cannot be carried out. Research and other issues to achieve fast results

Inactive Publication Date: 2010-02-24
FUDAN UNIV
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Problems solved by technology

Use a commercial bridge to measure ferroelectric capacitors. Since the voltage waveforms are sinusoidal or triangular waveforms, and the voltage sweep time is more than 1 second, the dielectric properties of ferroelectric film capacitors under fast voltage sweeps cannot be measured. The microscopic physical mechanism of the dielectric properties of electric film capacitors cannot be studied

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  • Method for measuring differential capacitance of ferroelectric film by rapid voltage sweep
  • Method for measuring differential capacitance of ferroelectric film by rapid voltage sweep
  • Method for measuring differential capacitance of ferroelectric film by rapid voltage sweep

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Embodiment Construction

[0019] The pulse signals required for the test are all edited by Agilent 81150A arbitrary waveform signal generator, the capacitor discharge current is recorded by LCWR 6200A oscilloscope, and the internal resistance of the system is 50 ohms.

[0020] 1. Measure the C-V curves of the ferroelectric film capacitance at different voltage sweep times.

[0021] Set the required test pulse waveform in the pulse generator, set the preset voltage V pret , reserve the relaxation time t r and scan start voltage V min , requiring V pret with V min The magnitude is consistent with the direction, and t r The time is much longer than the preset voltage scan time t w , set the change range of the measurement scan voltage V and the small voltage change ΔV. Then the discharge current is integrated by an oscilloscope connected to the sample, according to the formula:

[0022] ΔQ=|∫Idt|

[0023] C=ΔQ / ΔV(ΔV→0)

[0024] The C-V curves of different voltage sweep times were obtained.

[00...

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Abstract

The invention belongs to the technical field of performance test of solid dielectric medium, in particular to a method for measuring the differential capacitance of a ferroelectric film by rapid voltage sweep. Fully considering the contribution of different microcosmic ferroelectric domains in the film to a macroscopical capacitance value under the action of an external voltage, the method adoptsthe steps as following: remaining enough relaxation time after presetting impulse so that the pinning effect of charged charges on the microcosmic electric domains is reduced to the minimum; rapidly sweeping through the following impulse voltage with any amplitude, charging a capacitor, and enabling the capacitor of a ferroelectric film to generate corresponding discharging current through slightchange of the charging voltage; and calculating the discharging charges through an oscilloscope connected with a sample, thereby obtaining the corresponding differential capacitance. The invention solves the problem that a memercial electrical bridge cannot rapidly carry out voltage sweep, and provides an effectively measure for measuring the high-frequency response of the capacitance of the ferroelectric film and searching the contribution of microdefect movement to the dielectric response aspect.

Description

technical field [0001] The invention belongs to the technical field of solid dielectric performance testing, and in particular relates to a differential capacitance testing method of ferroelectric thin films. Background technique [0002] The characteristic of the dielectric is to transmit, store or record the action and influence of electricity in the form of electrode polarization in which the center of gravity of the positive and negative charges does not coincide. Therefore, the dielectric constant is the most basic parameter to characterize the dielectric. Ferroelectrics are a special class of dielectric materials with large dielectric constants, strong nonlinear effects, and significant temperature and frequency dependencies. The capacitance in the ferroelectric will decrease with time under the action of DC voltage, and the capacitance-voltage curve obtained when the voltage sweep time is greater than 1 second is butterfly-shaped. When the voltage sweep time is on th...

Claims

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Application Information

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IPC IPC(8): G01R27/26
Inventor 江安全刘骁兵
Owner FUDAN UNIV
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