Frequency dependence of negative capacitance in light-emitting devices

Trong, V. D.; Anh, Chu Thuy; Cương, Nguyễn Duy; Binh, Pham Thanh; Truong, Cong Thang; Pham, Anh T.

doi:10.1109/cce.2012.6315868

Cited by 2 publications

(4 citation statements)

References 9 publications

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“…Within this scope, a wide range of materials and structures were investigated to further develop the current understanding of NC-associated phenomena. Among them, semiconductor devices, including Schottky diodes [ 12 , 18 ], p-n junctions [ 19 ], heterojunctions [ 20 ] or metal-insulator-semiconductor structures [ 21 ], are well-known for exhibiting such behaviour [ 22 ]. Schottky junctions are one of the simplest rectifying systems, which can easily be processed between a metal and a semiconductor.…”

Section: Introductionmentioning

confidence: 99%

Evidence of Negative Capacitance and Capacitance Modulation by Light and Mechanical Stimuli in Pt/ZnO/Pt Schottky Junctions

Joly

Girod

Adjeroud

et al. 2021

Sensors

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We report on the evidence of negative capacitance values in a system consisting of metal-semiconductor-metal (MSM) structures, with Schottky junctions made of zinc oxide thin films deposited by Atomic Layer Deposition (ALD) on top of platinum interdigitated electrodes (IDE). The MSM structures were studied over a wide frequency range, between 20 Hz and 1 MHz. Light and mechanical strain applied to the device modulate positive or negative capacitance and conductance characteristics by tuning the flow of electrons involved in the conduction mechanisms. A complete study was carried out by measuring the capacitance and conductance characteristics under the influence of both dark and light conditions, over an extended range of applied bias voltage and frequency. An impact-loss process linked to the injection of hot electrons at the interface trap states of the metal-semiconductor junction is proposed to be at the origin of the apparition of the negative capacitance values. These negative values are preceded by a local increase of the capacitance associated with the accumulation of trapped electrons at the interface trap states. Thus, we propose a simple device where the capacitance values can be modulated over a wide frequency range via the action of light and strain, while using cleanroom-compatible materials for fabrication. These results open up new perspectives and applications for the miniaturization of highly sensitive and low power consumption environmental sensors, as well as for broadband impedance matching in radio frequency applications.

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Section: Introductionmentioning

confidence: 99%

Evidence of Negative Capacitance and Capacitance Modulation by Light and Mechanical Stimuli in Pt/ZnO/Pt Schottky Junctions

Joly

Girod

Adjeroud

et al. 2021

Sensors

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show abstract

“…The negative values of capacitance in Figure 1d) are however not predicted by the pn-junction theory, so there must be a different mechanism leading to the rapid disappearance of injected carriers. [11], [31] At the LED turn-on, the gradual increase is stopped and reverses until a steep decrease in capacity becomes visible. Finally, this ends in NC at the maximum EQE.…”

Section: A Negative Capacitance In Siqd-ledsmentioning

confidence: 99%

“…The electrical characteristics of an LED can be described by using Shockley's classical pn junction theory. [11] To uncover the effect of charge transport on the capacity behavior of the SiQD-LEDs, capacitance-voltage (C − V ) measurements are needed. C − V measurement is a powerful technique where an AC signal is superimposed on a DC bias and the electrical capacitance and conductance response of the device can be recorded as a function of the applied AC frequency.…”

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confidence: 99%

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Revealing the Negative Capacitance Effect in Silicon Quantum Dot Light-Emitting Diodes via Temperature-Dependent Capacitance-Voltage Characterization

et al. 2022

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In this study, quantum dot light-emitting diodes based on non-toxic silicon quantum dots functionalized with hexyl and dodecyl organic ligands showed a negative capacitance effect. Current density-voltage (J −V ) measurements revealed the charge transport mechanisms in the QLEDs. The capacitancevoltage (C − V ) characteristics were measured with an LCR meter over a wide range of frequencies (200 Hz to 1 MHz) and at temperatures from −40 • C to 60 • C. The classical heterojunction theory can describe the operation of quantum LEDs, but an effect not predicted by Shockley's theory was observed. Negative capacitance values were recorded in both fabricated LEDs, which were not observed in SiQD-LEDs before. Hence, we investigate the negative capacitance origin and its influence on the device performance. We attribute the negative capacitance to trapmediated recombination, where charges at defect sub-bandgap states contribute to the recombination but cannot be replenished fast enough. As a result, a current flows to re-establish the equilibrium, which lags behind the applied voltage, and the NC appears. By comparing the two functionalizations, we also observed a different temperature dependence of the positive capacitance peak and a stronger negative capacitance effect for dodecyl functionalized SiQDs. This effect is attributed to their improved charge carrier confinement abilities.Index Terms-Silicon quantum dot (SiQD), light-emitting diode (LED), negative capacitance (NC). I. INTRODUCTIONQ ANTUM dot light-emitting diodes (QLEDs) are highly researched as promising electroluminescence (EL) devices. QDs itself combine the advantages of inorganic and organic materials by offering size-tunable emission, [1] high color purity, [2] easy processibility, [3] and high photoluminescence quantum efficiency. [4] Additionally, QLEDs are expected to have improved stability compared to OLEDs because of their inorganic crystalline materials. [5] Many conventional QDs consist of toxic or heavy metal materials, such as Cd or Pb, and therefore, alternative materials are researched. A promising alternative is nanosized silicon,

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Frequency dependence of negative capacitance in light-emitting devices

Cited by 2 publications

References 9 publications

Evidence of Negative Capacitance and Capacitance Modulation by Light and Mechanical Stimuli in Pt/ZnO/Pt Schottky Junctions

Evidence of Negative Capacitance and Capacitance Modulation by Light and Mechanical Stimuli in Pt/ZnO/Pt Schottky Junctions

Revealing the Negative Capacitance Effect in Silicon Quantum Dot Light-Emitting Diodes via Temperature-Dependent Capacitance-Voltage Characterization

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