Effect Of Different Buffer Layers Research Articles

CHTS/Zn2P3-based solar cells with enhanced efficiency through ETL engineering: A numerical study

Copper Mercury Tin Sulfide (CHTS) solar cells have shown a promising performance in the field of photovoltaic energy conversion with a bandgap range between 1.0 eV and 1.5 eV. However, further improvement is required to enhance the efficiency of CHTS SCs. In our study, we conducted Numerical simulation of the investigation of the effect of different buffer layers and a Zn2P3 back-surface field (BSF) layer on the effectiveness of CHTS SCs using the SCAPS-1D Programming. Initially, we optimized the basic structure of a CHTS SC without a BSF layer. We evaluated three different buffer layers (GaN, In0.4Ga0.6N, and In0.65Ga0.35N) as potential insulating layers. GaN was found to be the optimal buffer strata, with a power conversion efficiency (PCE) of 19.89%. Next, we proposed a new device structure with a Zn2P3 BSF layer. The BSF layer was found to have a positive effect on cell effectiveness, increasing the PCE to 21.16%. We further investigated the effect of different input variables, such as carrier concentration, fault density, and thickness of the absorbed strata on the achievement of both apparatus structures, with and without the BSF layer. Our results showed that the device structure with the Zn2P3 BSF layer achieved a maximum PCE of 23.79%, which is significantly higher than the PCE of the apparatus structure in case of the absence of the BSF strata. This improvement in PCE is due to the reduced reassemble of the charge transporters behind the interface and the improved light absorption in the CHTS layer. Overall, our numeral conclusion suggests that the use of CHTS/GaN-based solar photovoltaic cell design with a Zn2P3. The BSF layer is considered an ideal choice for high-performance solar cells (SCs).

Enhancing the Performance of an Sb2Se3-Based Solar Cell by Dual Buffer Layer

In an Sb2Se3-based solar cell, the buffer layer is sandwiched between the absorber and the window layer, playing an essential role in interfacial electricity. Generally, CdS is used as a buffer layer, but its toxic nature and low bandgap can cause current loss because of parasitic absorption. In this work, we optimized the buffer layer by using ZnS as an alternative to the CdS buffer layer in order to decrease the use of CdS. The effect of different buffer layers on the solar device was explored by numerical simulation with the help of SCAPS 1D software. The basic parameters, such as open-circuit voltage (Voc), current density (Jsc), fill factor (FF), and efficiency (η) were analyzed and compared for both the buffer layers (CdS/ZnS). The results demonstrate that changing buffer materials and thicknesses has a significant impact on cell performance. The efficiency for the ZnS buffer layer was lower compared to that of the CdS-based solar cells because of insufficient energy band alignment. In order to enhance the efficiency of Sb2Se3-based solar cells, we used CdS/ZnS dual buffer layers and studied the device performance. The work function of the back contact also affects the device performance, and for work functions below 4.8 eV, the device’s efficiency was very low. The effect of varying the thicknesses and temperatures of the buffer layers on the I-V/C-V characteristics, quantum efficiency, and energy band structure are also reported. This study shall guide the researcher in reducing CdS and improving the device’s performance.

Numerical simulation of the effect of varied buffer layers on the performance of Cu(In, Ga)Se2 solar cells using Silvaco Tcad 2D

The CIGS thin-film solar cells Solar cells are regarded as one of the most promising photovoltaic technologies. They have the advantage of fast and low-cost manufacturing by depositing several thin layers. In this work, a numerical simulation was made to compare the effect of different buffer layers (CdS, ZnS, ZnSe, and In2S3) on the performance of CIGS solar cells using Silvaco Tcad 2D software. The results show that each buffer layer influences the performance of the cell. Therefore, our results suggest that the ZnS material as a buffer layers has better performance for our cell (Jsc=37.0252mAcm2, Voc=1,281, FF=88,01 , ƞ=20,88).

Development of high efficiency CZTS solar cell through buffer layer parameters optimization using SCAPS-1D

In this paper, numerical modelling and simulation using SCAPS-1D software have been carried out in order to investigate the effect of different buffer layers (CdS, CdSe and CdTe) on the efficiency of Cu2ZnSnS4 (CZTS) solar cells. The photovoltaic properties (open-circuit voltage (VOC), short-circuit current density (JSC), Fill Factor and Efficiency) have been studied at 300 K and under “AM 1.5 spectrum and one sun” by varying the thickness of the buffer and absorption layers, and the operating temperature. We found that the photovoltaic parameters of the solar cells are affected by the thickness change. Increasing the operating temperature has shown a negative effect on the solar cell performance, and the efficiency for all structures has been decreased with increasing temperature. At the optimum simulation parameters for all solar cell structures (50 nm buffer layer, 2000 nm CZTS absorber layer and operating temperature of 300 K), efficiency of 28.41%, 28.32% and 28.43% has been achieved for CdS, CdSe and CdTe, respectively. The present results can be considered as an important guideline for the fabrication of high-efficiency CZTS solar cell.

Effect of different buffer layers on the quality of InGaN layers grown on Si

This work studies the effect of four different types of buffer layers on the structural and optical properties of InGaN layers grown on Si(111) substrates and their correlation with electrical characteristics. The vertical electrical conduction of n-InGaN/buffer-layer/p-Si heterostructures, with In composition near 46%, which theoretically produces an alignment of the bands, is analyzed. Droplet elimination by radical-beam irradiation was successfully applied to grow high quality InGaN films on Si substrates for the first time. Among several buffer choices, an AlN buffer layer with a thickness above 24 nm improves the structural and optical quality of the InGaN epilayer while keeping a top to bottom ohmic behavior. These results will allow fabricating double-junction InGaN/Si solar cells without the need of tunnel junctions between the two sub-cells, therefore simplifying the device design.

The Effect of Buffer Layer on CNT Structure and CNT/Copper Interfacial Properties

ABSTRACTCarbon nanotubes (CNTs), with exceptional thermal and mechanical properties as well as inherently high surface area, are an attractive candidate for integrating into thermal structures of advanced power electronics. Growth of vertically aligned carbon nanotubes (VACNTs) directly onto copper (Cu) substrates is a promising approach to apply CNTs as novel thermal interface materials (TIMs) in electronics packaging. However, compared to growing CNTs on conventional inert substrates such as SiO2, direct growth of controllable CNT arrays onto Cu substrates is significantly more challenging due to the diffusion of metallic catalyst into the substrate during growth. By depositing an appropriate buffer layer on the Cu substrate surface, VACNTs of good alignment and high quality were reproducibly synthesized on the Cu substrate via the chemical vapor deposition (CVD) method in this study. The effect of different buffer layers on the CNT growth, nanotube structure and quality was investigated (SEM, Raman), particularly in terms of the interfacial properties between the CNT array and Cu substrate (Tensile compression force tester, Laser Flash Analysis). Our experimental results indicated that the buffer layer material, deposition method, and thickness play a key role in regulating the CNT layer growth/structure, leading to variable mechanical and thermal properties. The fundamental understanding thus obtained allows the successful synthesis of VACNT on copper substrates with desired structure and properties.

Effects of different buffer layers on the electro-luminescence performances in white organic light-emitting diodes

Abstract The effects of different hole injection materials as the buffer layer on the electro-luminescence (EL) performances of white organic light-emitting diodes (WOLEDs) are investigated in detail. It is found that the EL performances and electric properties were strongly dependent on the structure of the used hole injection materials with different thicknesses, which directly affected the injection and transport properties in devices, and thus the EL efficiency and lifetime. It can be seen that a hybrid buffer layer of 5 nm aluminum fluoride (AlF 3 )/15 nm 4,4′,4″-tris(3-methylphenylphenylamino) (m-MTDATA) as the hole injection buffer layer shows the best EL performances in efficiency and lifetime, showing a promising hole injection material in WOLEDs. The mechanisms behind the enhanced performance of the hybrid buffer layer in WOLEDs are discussed based on X-ray photoelectron spectroscopy (XPS) measurement.

Effect of different buffer layers on the microstructure and dielectric properties of BaTiO 3 thin films grown on Si substrates

Ferroelectric BaTiO 3 films were deposited on LaNiO 3 and Pt-buffered Si (1 0 0) substrates by radio frequency sputtering. The effect of different buffer layers on the corresponding orientation, crystallization, dielectric and leakage current properties of BaTiO 3 films was comparatively investigated. X-ray diffraction and atomic force microscope analysis demonstrate that the BaTiO 3 films on LaNiO 3 exhibit highly (1 0 0)-orientation with better crystallization, larger grain size, and smoother surface, while those on Pt show (1 1 1)-oriented structure with coarser surface morphology, due to the easier nucleation of BaTiO 3 (1 0 0) planes at the (1 0 0) LaNiO 3 surface. Electrical measurements indicate that the BaTiO 3 films on LaNiO 3 show larger dielectric constant and also higher leakage current density than those on Pt. The difference in electrical properties for the two BaTiO 3 films is suggested to be closely related to the various grain size and structural orientation on different buffer layers.

Solar-blind MSM-photodetectors based on Al xGa 1− xN/GaN heterostructures grown by MOCVD

Solar-blind MSM-photodetectors based on the AlGaN/GaN heterostructutes grown by MOCVD technology were fabricated and investigated. Directly on the MSM-diode we have measured a Schottky barrier height of 1.1 eV for Ni and 1.4 eV for Mo contacts on AlGaN. Effect of different buffer layers on the detector performances has been demonstrated. Detectors exhibit low dark currents and high sensitivity within the range of 250–290 nm. High-speed response of MSM-detectors is analyzed. Effect of optical excitation level on detector performance is discussed. At low excitation level the detector speed of response is limited by parasitic capacitance of interdigitated diode structure and by the transit time of the photogenerated carriers. At high excitation level the detector speed of response is limited by the field screening caused by the space-charge of the holes. The impulse response of AlGaN/GaN MSM-detector is compared favorably with GaAs MSM-device.

Growth modes, strain states, and electrical transport properties of epitaxial La 0.5Sr 0.5CoO 3 thin films grown on buffered Si substrates

By introducing different buffer layer, textured or epitaxial La 0.5Sr 0.5CoO 3 (LSCO) thin film can be prepared on Si substrate using pulsed laser deposition (PLD) method. Effects of different buffer layers on growth modes, strain states, and electrical transport properties of LSCO thin films were comparatively investigated. Due to small lattice constant mismatch (1.5%) and similarity of crystalline structure between LSCO and SrTiO 3 (STO), the LSCO film on the STO buffer layer is epitaxially grown with layer-by-layer (2D) mode, and the film is under tensile strain. However, owing to large lattice constant mismatch (9%), the LSCO film on the MgO buffer layer is c-axis textured with Stranski–Krastanow (S–K) growth mode, and tensile strain can be relaxed almost fully. Correspondingly, these LSCO films exhibit different electrical transport characteristics, such as electrical resistivity, T M I , etc., which can be ascribed to difference in growth modes and strain states of the LSCO films.

Effects of different buffer layers in flexible organic light-emitting diodes

In order to improve the luminance efficiency and flexibility of flexible organic light-emitting diodes (FOLEDs), a buffer layer was inserted between ITO and hole transport layer by spin coating. The buffer layer employed is poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), PEDOT:PSS/Teflon, N, N′-bis-(3-methylphenyl)- N, N′-bis-(phenyl)-benzidine (TPD) or bis[ N-(1-naphthyl)- N-phenyl]benzidine (α-NPD). The TPD and α-NPD were first solved in chloroform before spin coating. When 40 nm PEDOT:PSS was employed as buffer layer, the FOLED luminance efficiency increased from 2 to 4 cd/A in comparison with the original device without any buffer layer. If the buffer layer was PEDOT:PSS/Teflon, the luminance efficiency increased slightly to 4.4 cd/A. If α-NPD buffer layer was used, the luminance yield of the FOLED could be increased to levels ⩾5.5 cd/A.

Solar-blind MSM-photodetectors based on Al x Ga1-x N heterostructures

Solar-blind MSM photodetectors based on the AlGaN heterostructures have been fabricated and investigated. The influence of material properties on device parameters is discussed. Effect of different buffer layers on the detector performances has been examined. Detectors exhibit low dark currents and high sensitivity within the range of 250–290 nm. Effect of optical excitation energy on GaN-based MSM-detector performance is analyzed and discussed. At high excitation level the detector speed of response is limited by the field screening caused by the space-charge of the holes. The impulse response of GaN-based MSM-detector is compared favorably with GaAs MSM-device.

Comparison of the effect of PLT and PZT buffer layers on PZT thin films for ferroelectric materials applications

In order to study the effect of different buffer layers on the Pb(Zr0.52Ti0.48)O3 (PZT) thin films, 10-nm thick (Pb0.72La0.28)Ti0.93O3 (PLT) and Pb(Zr0.52Ti0.48)O3 buffer layers have been deposited on the Pt(1 1 1)/Ti/SiO2/Si substrates by pulsed laser deposition, respectively. The top buffer layers were also deposited on PZT thin films with the same thickness of the seed layers in order to enhance the fatigue characteristics of PZT thin films. We compared the results of dielectric constant, hysteresis loops and fatigue resistance characteristics. It was found that the dielectric properties of PZT thin films with PLT buffer layers were improved by comparing with PZT thin films with PZT buffer layers. The polarization characteristics of PZT thin films with PLT buffer layers were observed to be superior to those of PZT thin films using PZT buffer layers. The remanent polarization of PZT thin films showed 36.3 μC/cm2 and 2.6 μC/cm2 each in the case of use PLT and PZT buffer layers. For the switching polarization endurance analysis, PZT thin films with PLT buffer layers showed more excellent result than that of PZT thin films with PZT buffer layers.

Investigation of the influence of buffer and nitrided layers on the initial stages of InN growth on sapphire by MOCVD

InN is a very promising material for optoelectronics, high frequency devices and terahertz applications. However, there is no convenient matched substrate and, InN is usually grown onto sapphire. Due to the large lattice mismatch and the dissimilarity in atomic arrangement, the epitaxial growth of InN onto sapphire is a challenge. The initial stages of the growth are of primary importance for the obtention of high quality InN films. Epitaxial InN layers can be improved by nitriding the substrate but the quality of InN strongly depends on the temperature and time of nitridation used. We investigated the effect of these parameters on the crystalline quality, morphology, optical and electrical properties of InN layers. Raising the temperature and the time of nitridation is not beneficial. We also studied the effect of different buffer layers (GaN, AlN). Growth on template seems to be better than on low-temperature buffer (GaN and AlN). After optimising all parameters, we obtained InN layers on lightly nitrided sapphire which correspond, up to know and in our knowledge, to the best results in MOCVD low pressure: the layer growth mode is 2D, with a root mean square roughness of 0.62 nm, a reproducible mobility of 800 cm2/Vs and an electron concentration about 9 × 1018 cm–3. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Epitaxial lateral overgrowth of gallium nitride on silicon substrate

Many studies have been undertaken on how to reduce defects and dislocations in gallium nitride films due to the lattice mismatch and difference in thermal conductivity between GaN and the substrate. The ability of epitaxial lateral overgrowth (ELO) for extended defect reduction in the heteroepitaxial growth of III–V semiconductors has been demonstrated and utilized in the deposition of GaN. The purpose of this study is to experimentally investigate the effect of growth conditions on GaN film growth in the MOCVD process. The effect of different buffer layers was studied for the second growth of GaN in the ELO process. It was found that ELO significantly improved the morphology of GaN films. The best such films obtained in this work, as measured by X-ray rocking curve and photoluminescence, were obtained when a low-temperature GaN buffer layer was used prior to the deposition of the GaN seeding layer and the GaN overgrowth layer.

Giant magnetoresistance in Co/Cu multilayer thin films

This paper presents and discusses magnetic, magnetoresistive and structural properties of small grained, polycrystalline sputter-deposited Co/Cu multilayers. Of particular interest is the effect of different buffer-layers. GMR values are obtained in multilayers with little texture but with a well-defined layered structure.

Superconducting Y-Ba-Cu-O thin films on silicon and Al 2O 3 substrates

YBaCuO superconducting thin films have been prepared by sequential evaporation of copper, Y 2O 3 and BaF 2 layers on Si[100] and polycrystalline Al 2O 3 substrates. Such sequences were evaporated 1, 10 or 30 times on Si[100] with a 0.5 μm ZrO 2 buffer layer. The effects of different buffer layers were studied for Al 2O 3 substrates by means of the deposition of ZrO 2, copper, silver and BaTiO 3 layers with thicknesses of 20, 100 and 500 nm. The film properties were studied using electrical measurements, scanning electron microscopy, X-ray diffractometry, energy-dispersive X-ray spectrometry and secondary ion mass spectrometry. The best properties were obtained for the obtained on ZrO 2/Si[100] with a single evaporation sequence. The studies of the different buffers reveal a strong dependence of the film properties on the nature and thickness of the buffer, with the best results for films deposited on a silver layer.