Low Leakage Current Research Articles

Lead-Free BiFeO3 Thin Film: Ferroelectric and Pyroelectric Properties

The ferroelectric and pyroelectric properties of bismuth ferrite (BFO) epitaxial thin film have been investigated. The ferroelectric epitaxial thin layer has been deposited on strontium titanate (STO) (001) substrate by pulsed laser deposition, in a capacitor geometry using as top and bottom electrode a conductive oxide of strontium ruthenate (SRO). The structural characterizations performed by X-ray diffraction and atomic force microscopy demonstrate the epitaxial character of the ferroelectric thin film. The macroscopic ferroelectric characterization of BFO revealed a rectangular shape of a polarization-voltage loop with a remnant polarization of 30 μC/c m2 and a coercive electric field of 633 KV/cm at room temperature. Due to low leakage current, the BFO capacitor structure could be totally pooled despite large coercive fields. A strong variation of polarization is obtained in 80–400 K range which determines a large pyroelectric coefficient of about 10−4 C/m2 K deduced both by an indirect and also by a direct method.

High-k perovskite gate oxide for modulation beyond 1014 cm-2.

Scaling down of semiconductor devices requires high-k dielectric materials to continue lowering the operating voltage of field-effect transistors (FETs) and storing sufficient charge on a smaller area. Here, we investigate the dielectric properties of epitaxial BaHf0.6Ti0.4O3 (BHTO), an alloy of perovskite oxide barium hafnate (BaHfO3) and barium titanate (BaTiO3). We found the dielectric constant, the breakdown field, and the leakage current to be 150, 5.0 megavolts per centimeter (MV cm−1), and 10−4 amperes per square centimeter at 2 MV cm−1, respectively. The results suggest that two-dimensional (2D) carrier density of more than n2D = 1014 per square centimeter (cm−2) could be modulated by the BHTO gate oxide. We demonstrate an n-type accumulation mode FET and direct suppression of more than n2D = 1014 cm−2 via an n-type depletion-mode FET. We attribute the large dielectric constant, high breakdown field, and low leakage current of BHTO to the nanometer scale stoichiometric modulation of hafnium and titanium.

Aging Performance of Low-Density Polyethylene/Silicone Rubber Blends Insulators Under Contaminated Conditions

Insulation materials are a vital part of the electrical system in all kinds of high voltage (HV) Transmission lines. Environmental stresses affect the performance of all types of insulation materials over time. Dielectric breakdown strength (DBS), Hydrophobicity, Leakage current, internal partial discharge and volume resistivity are all three degraded parameters in the service environment. The materials stand best in outdoor insulation, with the lowest partial discharge, highest breakdown strength, high hydrophobic, Lowest Leakage current, and highest volume resistivity. Enhancement of these parameters is a potential avenue for many researchers over the period. In this study, low-density polyethene (LDPE) under different nanofillers, including SiO2, TiO2, TiO2@SiO2, with different weight percentages, are used. This study investigates the behaviour of dielectric breakdown strength (DBS), Hydrophobicity and Leakage Current (LC) for 1000h test under contaminated conditions such as High voltage, heat, ultraviolet (UV) radiations, salt fog, humidity, and acid rain.

Ferroelectric capacitor with an asymmetric double-layer PLZT structure for FRAM

We developed a lanthanum-doped Pb(Zr0.4,Ti0.6)O3 (PLZT)-based ferroelectric capacitor for low-voltage operation of ferroelectric memory for use in edge devices in the internet of things. The structure, consisting of PLZT stacked layers 30 and 90 nm thick, showed drastically improved performance in three main measures: low leakage current, high saturation polarization, and low saturation voltage. Secondary ion mass spectroscopy indicated that atomic interdiffusion between PLZT and IrOx in the top electrode (TE) was suppressed by the 30 nm thick PLZT, which plays the role of a diffusion barrier, producing a low leakage current and high saturation polarization. The higher oxygen atomic density of the PLZT near the TE interface lowers the oxygen vacancy, which should also suppress the leakage current and the P–V hysteresis shift (imprint). The large grain size and high crystalline quality of PLZT near the TE interface in the PLZT structure provide a high saturation polarization with low leakage current.

Understanding the Sidewall Passivation Effects in AlGaInP/GaInP Micro-LED

The passivation effects of sulfur treatment and Al2O3 passivation for AlGaInP/GaInP red micro-light-emitting-diodes (LEDs) were investigated in terms of the external quantum efficiency (EQE) and the current density showing the peak EQE (JEQE, peak). We systematically compared the electrical and optical characteristics of the micro-LEDs with and without passivation according to various sizes. Interestingly, our investigation indicated that simple electrical characteristics such as current density–voltage property are difficult to precisely reflect the minor change in electrical properties due to passivation when the device has the inherently low leakage current. Whereas the EQE was enhanced by 20% and JEQE, peak was largely shifted to a lower current density region at the LED with a size of 15 × 15 μm2. To examine the passivation effects, we carefully analyzed the EQE and JEQE, peak with the ABC recombination model, and established the methodology to investigate the influence of a sidewall in micro-LEDs. As a result, we extracted the surface recombination velocity regarding the surface passivation, showing a nearly 14% reduction with the passivation.

Ultra-Deep Annular Cu Through-Silicon-Vias Fabricated Using Single-Sided Process

Ultra-deep through-silicon-vias (TSVs) are of great demand for 3D heterogeneous integration. However, most reported deep TSVs adopt double-sided silicon etching and electroplating, which dramatically increases the complexity and cost of the fabrication process. This letter focuses on how to achieve a high-quality Cu seed layer in ultra-deep vias, which is the key technology for the fabrication of single-sided ultra-deep TSVs. By proposing a novel pulsed ultrasound-assisted electroless plating method, continuous and dense Cu seed layers are successfully deposited in silicon vias with a depth as large as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$580 ~\mu \text{m}$ </tex-math></inline-formula> . Combined with a conformal Cu electroplating and a vacuum-assisted Benzocyclobutene (BCB) refilling, BCB-core annular Cu TSVs with depths up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$580 ~\mu \text{m}$ </tex-math></inline-formula> and aspect ratios up to 8 are successfully fabricated. Measured results show that the fabricated TSVs exhibit a depletion capacitance of 1.75 pF, a low leakage current of 0.44 pA at 20 V, indicating good electrical properties.

Electrical characterization of memory capacitors for nonvolatile memory applications based on nanolaminated HfO2/Al2O3 and Al-doped HfO2 stacks

Memory capacitors with atomic-layer-deposited HfO2/Al2O3 nanolaminated layers and Al-doped HfO2 charge trapping layers were investigated through capacitance-voltage (C-V) and current-voltage (I-V) measurements. The dielectric constant of the multi-dielectric stack comprising 20-nm Al2O3 blocking oxide, a HfO2-based layer and 2.4-nm tunnel SiO2 does not depend on the manner of Al-introduction in HfO2.The stacks exhibit a negative oxide charge of about -5.1×1011 cm−2 and -2.5×1011 cm−2 for the structures with nanolaminated and doped layers, respectively. The Al-doping of HfO2 is found to produce lower leakage currents. A sublinear behavior of the current-voltage curves is observed in the range of -20 ÷ +10 V for both HfO2-based stacks. Memory windows of ∼ 1 V when charging with ±27-V voltage pulses are obtained; the data suggests that electron trapping is better pronounced in the HfO2/Al2O3 nanolaminate, while positive charge accumulation prevails in the Al-doped HfO2 layers.

Performance of in situ oxidized platinum/iridium alloy Schottky contacts on (001), (2¯01), and (010) β -Ga2O3

The performance of β-Ga2O3 Schottky contacts (SCs) fabricated using amorphous, intentionally oxidized platinum–iridium alloys was investigated as a function of alloy composition and β-Ga2O3 crystal orientation. PtyIr(1−y)Ox SCs with Pt fractions of y = 0.8, 0.5, and 0.3 were deposited on (001), (2¯01), and (010) single-crystal β-Ga2O3 substrates via the reactive rf and dc co-sputtering of Pt and Ir targets using oxygen–argon plasmas. In each case, the PtyIr(1−y)Ox SCs were highly rectifying with current rectification ratios (at ±3 V) of 11/10/9 orders of magnitude (at 300 K) for the (001)/(2¯01)/(010) β-Ga2O3 substrates. Current–voltage (I–V) and capacitance–voltage (C–V) measurements revealed that the Pt0.5Ir0.5Ox SCs contained the highest Schottky barriers on all β-Ga2O3 crystal faces, with the best contacts having ideality factors of 1.05 and image-force-corrected I–V and C–V determined barrier heights of 2.10 and 2.20 eV, respectively. These were consistently higher by ∼0.2 eV than the corresponding barriers for the Pt0.8Ir0.2Ox and Pt0.3Ir0.7Ox SCs, with the Pt0.5Ir0.5Ox SCs also having significantly lower reverse leakage currents (in the 0 to −100 V range). In comparison, the barrier heights of the best unoxidized plain-metal Pt0.5Ir0.5 SCs were only ∼1.2 eV, illustrating the effectiveness of in situ oxidation in improving the performance of PtIr SCs. All PtyIr(1−y)Ox SCs on (2¯01) β-Ga2O3 showed excellent high-temperature performance with rectification ratios (at ±3 V) of 109 at 300 °C and of 106 at 500 °C.

Integration of fully printed and flexible organic electrolyte-based dual cell supercapacitor with energy supply platform for low power electronics

We report the fabrication of flexible, printed dual cell supercapacitors (DCSCs) and their implementations in energy storage units providing peak power to portable devices. The use of organic electrolytes enhances higher capacity in both potential windows (2.5 V/cell) and the temperature ranges than the aqueous electrolytes, while propylene carbonate retains the advantages of low cost and low toxicity. The device delivered capacitance value between 3 and 4 mF, equivalent series resistance < 2 Ω, and very low leakage current of about 0.1 µA. We demonstrated the integration of an organic photovoltaic module (OPV) with an energy supply platform (ESP) and DCSCs for indoor light energy harvesting and storage. The maximum harvested energy was about 39 mJ. The energy is sufficient to provide peak power to portable devices and sensors. This was confirmed by powering an LED with our energy harvesting system. Mechanical deformation testing of DCSCs shows excellent mechanical stability, so that the device is well suited for flexible energy storage units. In a long-term cyclic stability test, the decrease in capacitance value was only 1% of the initial value after 10,000 cycles, indicating good durability and performance.

Surface‐Oxide‐Controlled InAlGaN/GaN High‐Electron‐Mobility Transistors Using Al2O3‐Based Insulated‐Gate Structures with H2O Vapor Pretreatment

Herein, Al2O3/InAlGaN/GaN metal–insulator–semiconductor high‐electron‐mobility transistors (MIS‐HEMTs) using H2O vapor pretreatment to decrease the amount of deficient indium oxide (InOx) is successfully developed. InOx acts as an electron trap in the oxide on the surface of the InAlGaN barrier layer. It is clarified that when O2 plasma is used as an oxidant source for atomic‐layer‐deposited (ALD) Al2O3 (O2 plasma‐Al2O3), the forward breakdown voltage increases using the MIS‐HEMT, due to a high density and a low leakage current of O2 plasma‐Al2O3. Furthermore, when using O2 plasma‐Al2O3 for InAlGaN/GaN MIS‐HEMTs, H2O vapor pretreatment is effective in decreasing the amount of InOx and electron traps in the oxide on the surface, thus suppressing current collapse. These results demonstrate the improved output power characteristics of the fabricated Al2O3/InAlGaN/GaN MIS‐HEMT and show the potential of surface‐oxide‐controlled MIS structures as promising process technologies for next‐generation high‐power radio frequency devices.

Effects of oxygen sources on properties of atomic-layer-deposited ferroelectric hafnium zirconium oxide thin films

Orthorhombic HfxZr1-xO2 (HZO) is a promising ferroelectric material for realizing ferroelectric devices in the modern semiconductor industry because of its excellent CMOS compatibility and scalability. Atomic layer deposition (ALD) facilitates the growth of robust ferroelectric HZO films that can be used in nanoelectronic devices. Herein, we provide a comprehensive understanding of the effects of the oxygen source, either H2O or O3, on the properties of ALD-grown HZO films. Although the growth per cycle promoted by ALD does not change with the type of oxygen source, the impurity content of the HZO film grown with H2O are higher than that with O3. The low impurity content of the HZO film grown with O3 results in low leakage current. The ALD process with O3 further suppresses the emergence of the nonferroelectric monoclinic phase in the ferroelectric orthorhombic HZO matrix. Consequently, the HZO film grown with O3 exhibits a small coercive field for ferroelectric domain switching and high electrical reliability. This study demonstrates that O3 is more favorable for growing high-quality HZO films via ALD by using metal precursors comprising tetrakis(ethylmethylamino) ligands.

High RF Performance GaN-on-Si HEMTs With Passivation Implanted Termination

This work reports recent progress in the sub-6 GHz power performance of GaN-based HEMTs grown on high resistivity silicon substrates with passivation implanted termination (PIT) process. Thanks to the mitigated electric field crowding at the gate edge and the suppressed negative fixed charge-induced carrier depletion, the fabricated HEMTs demonstrate a low leakage current, a high ON/OFF current ratio of 10⁸, and improved breakdown voltage associated with a current collapse at 40 V drain quiescent condition of as low as 5.6&#x0025;. S-band continuous-wave large signal measurements yield a high power-added efficiency (PAE) of 69&#x0025;, a drain efficiency (DE) of 72&#x0025;, and an output power density (<inline-formula> <tex-math notation="LaTeX">${P}_{\text{out}}$ </tex-math></inline-formula>) of 7.2 W/mm at <inline-formula> <tex-math notation="LaTeX">${V}_{\text{DS}}=30$ </tex-math></inline-formula> V. Moreover, the transistor delivers a maximum <inline-formula> <tex-math notation="LaTeX">${P}_{\text{out}}$ </tex-math></inline-formula> up to 10.2 W/mm with a peak PAE of 63.8&#x0025; at <inline-formula> <tex-math notation="LaTeX">${V}_{\text{DS}}=40$ </tex-math></inline-formula> V. The PAE and <inline-formula> <tex-math notation="LaTeX">${P}_{\text{out}}$ </tex-math></inline-formula> as a function of drain bias indicate that the transistors remain constant high PAE and linearly increased <inline-formula> <tex-math notation="LaTeX">${P}_{\text{out}}$ </tex-math></inline-formula> over a wide range of drain voltage variation. These excellent results have demonstrated the PIT process could be an attractive technique to facilitate the application of high-performance and cost-competitive GaN-on-Si HEMTs for 5G wireless base stations.

A Simple Route to Produce Highly Efficient Porous Carbons Recycled from Tea Waste for High-Performance Symmetric Supercapacitor Electrodes.

High-performance porous carbons derived from tea waste were prepared by hydrothermal treatment, combined together with KOH activation. The heat-treatment-processed materials possess an abundant hierarchical structure, with a large specific surface of 2235 m2 g−1 and wetting-complemental hydrophilicity for electrolytes. In a two-electrode system, the porous carbon electrodes’ built-in supercapacitor exhibited a high specific capacitance of 256 F g−1 at 0.05 A g−1, an excellent capacitance retention of 95.4% after 10,000 cycles, and a low leakage current of 0.014 mA. In our work, the collective results present that the precursor crafted from the tea waste can be a promising strategy to prepare valuable electrodes for high-performance supercapacitors, which offers a practical strategy to recycle biowastes into manufactured materials in energy storage applications.

RF/Analog and Linearity Performance Evaluation of Lattice-matched Ultra-thin AlGaN/GaN Gate Recessed MOSHEMT with Silicon Substrate

In this article, the authors have demonstrated and analyzed various analog/RF, and linearity performances of an AlGaN/GaN gate recessed MOSHEMT (GR-MOSHEMT) grown on a Si substrate with mathematical modeling based Technology Computer-Aided Design (TCAD) simulation. Specifically, an Al2O3 dielectric GR-MOSHEMT has shown tremendous potential in terms of AC/DC figure of merits (FOM’s) such as low leakage current, high transconductance, high Ion/Ioff current ratio, and excellent linear properties corresponding to conventional AlGaN/GaN HEMT and MOSHEMT. The figure-of-merit metrics such as VIP2, VIP3, IIP3, and IDM3 are performed for the different drain to source voltages (VDS) of 2.5 V, 5 V, and 10 V. All the modeling and simulation results are generated by Commercial Silvaco TCAD and found to be satisfactory in terms of high frequency and power applications. The present GR-MOSHEMT device shows superior performance with a threshold voltage of 0.5 V, a Current density of 888 mA, a high transconductance of 225 mS/mm, and a high unit gain cut-off frequency 0.91GHz. The developed AlGaN/GaN GR-MOSHEMT considerably improves the device performance and is also suitable for high power distortion-less RF applications.

Role of B-site disorder in the properties of lead-free Na0.5Bi0.5(Mg1/3Nb2/3)O3 ceramic: A possible electrocaloric material with low leakage current

The electrocaloric (EC) effect in ferroelectric materials has been studied extensively to develop materials for solid-state cooling applications. The Na0.5Bi0.5TiO3-based ferroelectric material is selected for this particular application. The Ti4+ of the lead-free Na0.5Bi0.5TiO3 is completely replaced by (Mg1/3Nb2/3)4+ to enhance the dielectric breakdown strength and to observe the EC effect. The lead-free Na0.5Bi0.5(Mg1/3Nb2/3)O3 is synthesized via the columbite route with optimized processing conditions. The material shows a frequency-independent high ferroelectric–paraelectric transition temperature (460 °C) with a slim polarization vs electric field loop. The adiabatic temperature change (ΔT) of the compound is evaluated from the temperature-dependent polarization behavior, and calculated ΔT is ≈ 0.135 K at room temperature. The room-temperature EC strength and leakage current of the material are examined to check its suitability for solid-state refrigeration.

Investigation of AlGaN/GaN Schottky barrier diodes on free-standing GaN substrate with low leakage current

Benefiting from the excellent properties of GaN with a wide bandgap of 3.4 eV as well as high critical field of 3.3 MV/cm, GaN-based devices prove to be a promising candidate in extreme conditions. Especially, high-density high-mobility two-dimensional electron gas (2DEG) induced by spontaneous piezoelectric polarization in AlGaN/GaN heterostructure enables AlGaN/GaN device to lower on-resistance (&lt;i&gt;R&lt;/i&gt;&lt;sub&gt;ON&lt;/sub&gt;). However, owing to the lack of free-standing GaN substrate with large size and high quality, the epitaxis of GaN is always based on hetero-substrate such as Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;, Si and SiC, which shows large lattice mismatch and thermal mismatch. The large mismatch between GaN and substrate leads to high dislocation as well as high leakage current (&lt;i&gt;I&lt;/i&gt;&lt;sub&gt;R&lt;/sub&gt;) of GaN devices. In this work, high-performance AlGaN/GaN Schottky barrier diode with low &lt;i&gt;I&lt;/i&gt;&lt;sub&gt;R&lt;/sub&gt; and low turn-on voltage (&lt;i&gt;V&lt;/i&gt;&lt;sub&gt;ON&lt;/sub&gt;) is fabricated on a 3-inch free-standing GaN substrate with C-doping GaN buffer layer to suppress &lt;i&gt;I&lt;/i&gt;&lt;sub&gt;R&lt;/sub&gt;. Owing to the suppressed dislocation density of the AlGaN/GaN epitaxial wafer on free-standing substrate, low Ohmic contact resistance (&lt;i&gt;R&lt;/i&gt;&lt;sub&gt;C&lt;/sub&gt;) is difficult to achieve the suppressed penetration of Ohmic metal into 2DEG channel, which is adverse to the high current density. In this work, a low &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;C&lt;/sub&gt; of 0.37 Ω·mm is obtained by one-step self-aligned Ohmic process, including the etching of partial AlGaN barrier layer and lift-off of Ohmic metal. The 2DEG is formed under the effect of residual AlGaN barrier layer, and the short distance between 2DEG and Ohmic metal contributes to lowering the value of &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;C&lt;/sub&gt;. The groove anode region is defined by the low damaged inductively coupled plasma process with a low etching rate of 1 nm/min, and the total depth is 35 nm, confirmed by atomic force microscope. Fully removing the AlGaN barrier layer from the anode region makes the anode metal directly contact the 2DEG channel, thereby improving the performance of the fabricated AlGaN/GaN Schottky barrier diode (SBD) with a low &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;ON&lt;/sub&gt; of 0.67 V, low &lt;i&gt;I&lt;/i&gt;&lt;sub&gt;R&lt;/sub&gt; of 3.6 × 10&lt;sup&gt;–8&lt;/sup&gt; A/mm, and an &lt;i&gt;I&lt;/i&gt;&lt;sub&gt;ON&lt;/sub&gt;/&lt;i&gt;I&lt;/i&gt;&lt;sub&gt;OFF&lt;/sub&gt; ratio of up to 3 × 10&lt;sup&gt;7&lt;/sup&gt;. The values of differential &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;ON,sp&lt;/sub&gt; are calculated to be 0.44, 0.86, 1.59, 2.55 mΩ·cm&lt;sup&gt;2&lt;/sup&gt; for GaN SBDs with various values of &lt;i&gt;L&lt;/i&gt;&lt;sub&gt;AC&lt;/sub&gt; of 6, 10, 15, 20 μm, and the values of &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;ON,sp&lt;/sub&gt; determined at an anode current density of 100 mA/mm are 1.27, 2.08, 3.29, 4.63 mΩ·cm&lt;sup&gt;2&lt;/sup&gt;, respectively. As the measured temperature increases from 300 to 425 K, the &lt;i&gt;I&lt;/i&gt;&lt;sub&gt;R&lt;/sub&gt; is increased only by 3 times to 1.6 × 10&lt;sup&gt;–7&lt;/sup&gt; A/mm, which shows the great potential for next-generation power electronics.

Sidewall-Implanted Trench Termination for 4H-SiC Devices With High Breakdown Voltage and Low Leakage Current

In this letter, a sidewall-implanted trench termination for SiC devices is proposed and experimentally demonstrated. With the p-type sidewall region implemented by tilted ion implantation, the electric field crowding at the edge of the main junction can be alleviated. Compared with the conventional trench termination, devices with the fabricated sidewall-implanted trench termination exhibits a higher breakdown voltage ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BV</i> ) exceeding 1800V, as well as lower leakage current. Moreover, the minimum trench width for over 1800V blocking is significantly reduced from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$14~\mu \text{m}$ </tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5~\mu \text{m}$ </tex-math></inline-formula> . In addition, the sidewall-implanted trench termination shows stronger robustness as the dominant current path is relocated from the trench sidewall to the whole active region.

Hybrid La2O3-cPVP Dielectric for Organic Thin Film Transistor Applications

In this work, we have studied the electrical performance of cross-linked polyvinyl phenol (cPVP) modified lanthanum oxide (La2O3) bilayer dielectric film in pentacene thin film transistors (TFT). A simple spin-coating and room temperature operated cross-linking reaction of the hydroxyl moieties of PVP and the nitrogen groups of PMF were carried out to form the cross-linked PVP. The deposition of a thin 30 nm cPVP layer over the La2O3 layer provided a low leakage current (<10−7 A cm−2), causing a reduction in the interface trap density. Besides, the modified surface properties of the La2O3 layer were favorable for the growth of pentacene organic semiconductors. As a result, the current on-off ratio and the sub-threshold slope was improved from 104 and 1.0 V/decade to 105 and 0.67 V/decade. The La2O3∕cPVP pentacene TFT operated at −10 V also exhibited improvement in the field-effect mobility to 0.71 cm2 Vs−1 from 0.48 cm2 Vs−1 for the single-layer La2O3 (130 nm) device. Thus, our work demonstrates that the rare earth oxide La2O3 with cPVP is an excellent dielectric system in the context of emerging transistors with hybrid polymer gate dielectrics.

Electrical Properties of Compositional Al&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; Supplemented HfO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; Thin Films by Atomic Layer Deposition

With advanced research for dielectrics including capacitors in DRAMs, decoupling filters in microcircuits and insulating gates in transistors, a lot of demand for the new challenging of high-k materials in semiconductor industries has been emerged. This study explores and addresses the experimental approach for composite materials with one of the major concerns of high capacitance, and low leakage, as well as ease of integration technology. The characteristics of Al2O3 supported HfO2 (AHO) thin films for a series of different Hf ratios with Al2O3 dielectrics by atomic layer deposition demonstrated as a candidate material. A composite AHO films with the homogeneous compositions of Al and Hf atoms into the Al-Hf-O mixed oxide system could stabilize the polycrystalline structure with increasing of dielectric constant (k) and decreasing of leakage current density, as well as a higher breakdown voltage than HfO2 film on its own. 70 nm thick AHO thin films with different composition of Al and Hf contents were prepared by atomic layer deposition technique on titanium nitride (TiN) and silicon dioxide (SiO2) coated Si substrates. Photolithography and metal lift-off technique were used for the device fabrication of the metal-insulator-metal (MIM) capacitor structures. AHO films on TiN/SiO2/Si were measured by semiconductor analyzer and source/ measure system with probe station in the voltage range from -5 to 5 V with a frequency range from 10 kHz to 1 MHz were used to conduct capacitance-voltage (C-V) measurements with low/medium frequency range and current-voltage (I-V) measurements. It was found that Au/AHO/TiN/SiO2/Si MIM capacitors demonstrate a capacitance density of 1.5 - 4.5 fF/μm2 at 10 kHz, a loss tangent of 0.02 - 0.04 at 10 kHz, dielectric constant of 11.7 - 35.5 depending on the composition and a low leakage current of 1.7 × 10-9 A/cm2 at 0.5 MV/cm at room temperature. The acquired experimental results could show the possibility of compositional alloy thin films that could potentially replace or open new market for high-k challenges in semiconductor technology.

Плазмохимическое травление в постростовой технологии фотоэлектрических преобразователей

Investigation of the heterostructure plasmachemical etching technology for fabricating multi-junction photovoltaic converters has been carried out. The dividing mesa-structure forming stage at different etching regimes and subsequent disturbed layer removing by liquid chemical treatment has been reviewed. The influence of mesa etching methods on cells photovoltaic characteristics has been investigated. Developed was the technology of photovoltaic converters fabrication with low current leakage values less than 10-9 A at voltage less then 1 V with high resistance to degradation.