Ionic-to-electronic current amplification in hybrid perovskite solar cells: ionically gated transistor-interface circuit model explains hysteresis and impedance of mixed conducting devices

Mobile ions in hybrid perovskite semiconductors introduce a new degree of freedom to electronic devices suggesting applications beyond photovoltaics. An intuitive device model describing the interplay between ionic and electronic charge transfer is needed to unlock the full potential of the technology. We describe the perovskite-contact interfaces as transistors which couple ionic charge redistribution to energetic barriers controlling electronic injection and recombination. This reveals an amplification factor between the out of phase electronic current and the ionic current. Our findings suggest a strategy to design thin film electronic components with large, tuneable, capacitor-like and inductor-like characteristics. The resulting simple equivalent circuit model, which we verified with time-dependent drift-diffusion simulations of measured impedance spectra, allows a general description and interpretation of perovskite solar cell behaviour

Monoclinic Zirconium Oxide Nanostructures Having Tunable Band Gap Synthesized under Extremely Non-Equilibrium Plasma Conditions

Zirconium oxide (ZrO2) is a wide and direct band gap semiconductor used for the fabrication of optoelectronic devices. ZrO2 based optoelectronic devices span a wide optical range depending on the band gap of ZrO2 material. The band gap of ZrO2 can be tuned by fabricating it to the nanoscale. In this paper, we synthesized the ZrO2 nanostructures on quartz substrate using ZrO2 ions produced by the ablation of ZrO2 pellet due to high temperature, high density, and extremely non-equilibrium argon plasma in a modified dense plasma focus device. Uniformly distributed monoclinic ZrO2 nanostructures with an average dimension of ~14 nm were obtained through X-ray diffraction and scanning electron microscopy studies. The monoclinic phase of ZrO2 nanostructures is further confirmed from photoluminescence (PL) and Raman spectra. PL spectra show peaks in ultra-violet (UV), near-UV, and visible regions with tunable band gap of nanostructures. A similar tunability of band gap was observed from absorption spectra. The obtained structural, morphological, and optical properties are compared to investigate the potential applications of ZrO2 nanostructures in optoelectronic devices

Dense plasma focus-based nanofabrication of III–V semiconductors: Unique features and recent advances

The hot and dense plasma formed in modified <i>dense plasma focus</i> (DPF) device has been used worldwide for the nanofabrication of several materials. In this paper, we summarize the fabrication of III–V semiconductor nanostructures using the high fluence material ions produced by hot, dense and extremely non-equilibrium plasma generated in a modified DPF device. In addition, we present the recent results on the fabrication of porous <i>nano-gallium arsenide</i> (GaAs). The details of morphological, structural and optical properties of the fabricated nano-GaAs are provided. The effect of rapid thermal annealing on the above properties of porous nano-GaAs is studied. The study reveals that it is possible to tailor the size of pores with annealing temperature. The optical properties of these porous nano-GaAs also confirm the possibility to tailor the pore sizes upon annealing. Possible applications of the fabricated and subsequently annealed porous nano-GaAs in transmission-type photo-cathodes and visible optoelectronic devices are discussed. These results suggest that the modified DPF is an effective tool for nanofabrication of continuous and porous III–V semiconductor nanomaterials. Further opportunities for using the modified DPF device for the fabrication of novel nanostructures are discussed as well

Dense Plasma Focus-Based Nanofabrication of III–V Semiconductors: Unique Features and Recent Advances

The hot and dense plasma formed in modified dense plasma focus (DPF) device has been used worldwide for the nanofabrication of several materials. In this paper, we summarize the fabrication of III–V semiconductor nanostructures using the high fluence material ions produced by hot, dense and extremely non-equilibrium plasma generated in a modified DPF device. In addition, we present the recent results on the fabrication of porous nano-gallium arsenide (GaAs). The details of morphological, structural and optical properties of the fabricated nano-GaAs are provided. The effect of rapid thermal annealing on the above properties of porous nano-GaAs is studied. The study reveals that it is possible to tailor the size of pores with annealing temperature. The optical properties of these porous nano-GaAs also confirm the possibility to tailor the pore sizes upon annealing. Possible applications of the fabricated and subsequently annealed porous nano-GaAs in transmission-type photo-cathodes and visible optoelectronic devices are discussed. These results suggest that the modified DPF is an effective tool for nanofabrication of continuous and porous III–V semiconductor nanomaterials. Further opportunities for using the modified DPF device for the fabrication of novel nanostructures are discussed as well

Metal-insulator-metal capacitors based on lanthanum oxide high-k dielectric nanolayers fabricated using dense plasma focus device

Metal-insulator-metal (MIM) capacitors with lanthanum oxide (La2O3) high-κ dielectric, for potential applications in mixed-signal integrated circuit (IC), have been fabricated using a dense plasma focus device. The electrical characteristics and morphological properties of the fabricated nanodevices are studied. The MIM capacitors were further annealed to enhance the electrical properties in terms of the low leakage current density, the high capacitance density, and the improved capacitance voltage linearity. The minimum leakage current densities of ∼1.6 × 10−9 A/cm2 and ∼2.0 × 10−10 A/cm2 at −1 V are obtained along with the maximum capacitance densities of ∼17.96 fF/μm2 at 100 kHz and ∼19.10 fF/μm2 at 1 MHz, 0 V for as-fabricated and annealed MIM capacitors having 15 nm thick dielectric layers as measured using ellipsometry. The nanofilms with the minimum root mean square roughness of ∼10 nm are examined using atomic force microscopy. The results are superior compared to some other MIM capacitors and can be optimized to achieve the best electrical parameters for potential applications in radio frequency (RF)/mixed signal ICs. The high frequency C-V measurements indicate an increase in the capacitance density upon increasing the frequency which supports the possibility of potential high-frequency/RF applications of the MIM capacitors