Engineering CuInGaSSe2 Surface Properties to Enhance Device Performance

2003 ◽  
Vol 796 ◽  
Author(s):  
Shalini Menezes ◽  
Yan Li ◽  
Sharmila J. Menezes
Keyword(s):  
Surface Defects ◽  
Lattice Mismatch ◽  
Defect Density ◽  
Dynamic Equilibrium ◽  
Spectral Response ◽  
Buffer Layers ◽  
Device Performance ◽  
Air Oxidation ◽  
Special Effect ◽  
Response Measurement

ABSTRACTThe CuInGaSSe2/CdS heterostructure interface has a special effect on the performance of an important thin film photovoltaic device. The CdS buffer layer is essential to stabilize the performance of CuInGaSSe2 based devices. It adjusts the lattice mismatch at the absorber/window interface, repairs CuInGaSSe2 surface defects and protects it from air oxidation. Unfortunately, the CdS material has many environmental issues. This paper reports an alternate chemical approach to engineer the interface defects in CuInGaSSe2 and maximize its PV output. It describes a simple processing step to manipulate the defect density. This step could potentially reduce sensitivity to the ambience, widen the surface bandgap and replace the current hazardous processes used in state-of-the-art CuInGaSSe2 modules. Photocurrent and spectral response measurement in an electrolytic medium monitor the effects of surface modification, specific metal ions and time. The CuInGaSSe2 films respond easily to a number of external stimuli with either positive or negative changes in the electro-optic properties. Strong time dependence of the photocurrent suggests a dynamic equilibrium of point defects in the CuInGaSSe2 film. The results provide new insights into the effects of stoichiometry, deposition methods and oxide formation, on the defect chemistry. They also provide directions for reconfiguring the deep defects for enhanced device performance without the need for toxic etchants or buffer layers, and the environmental hazards associated with these steps.

Attainment of Stable (FTO/ZnO/CdS/CH3NH3SnI3/GaAs/Au) Perovskite Solar Cell With Above 23% Photovoltaic Performance Using Solar Capacitance Simulator

2021 ◽  
Author(s):  
Irfan Qasim ◽  
Owais Ahmad ◽  
Asim Rashid ◽  
Tashfeen Zehra ◽  
Muhammad Imran Malik ◽  
...  
Keyword(s):  
Solar Cells ◽  
Defect Density ◽  
Short Circuit ◽  
Photovoltaic Performance ◽  
Hole Transport ◽  
Transport Layer ◽  
Buffer Layers ◽  
Electron Transport Layer ◽  
Device Performance ◽  
Highly Efficient

Abstract Solar energy is found to be low cost and abundant of all available energy resources and needs exploration of highly efficient devices for global energy requirements. We have investigated methyl ammonium tin halide (CH3NH3SnI3)-based perovskite solar cells (PSCs) for optimized device performance using solar capacitance simulator SCAPS-1D software. This study is a step forward towards availability of stable and non-toxic solar cells. We explored all necessary parameters such as metal work functions, thickness of absorber and buffer layers, charge carrier’s mobility and defect density for improved device performance. Calculations revealed that for the best efficiency of device the maximum thickness of the perovskite absorber layer must be 4.2 μm. Furthermore, optimized thickness values of (ZnO=0.01 μm) as electron transport layer (ETL), GaAs as hole transport layer (HTL=3.02 μm) and (CdS=10 nm) and buffer layer have provided power conversion efficiency (PCE) of 23.53%. Variation of open circuit voltage (Voc), Short circuit current (Jsc), Fill Factor (FF%) and quantum efficiency against thickness of all layers in FTO/ZnO/CdS/CH3NH3SnI3/GaAs/Au compositions have been critically explored and reported. Interface defects and defect density in different inserted layers have also been reported in this study as they can play a crucial for the device performance. Insertion of ZnO layer and CdS buffer layers have shown improved device performance and PCE. Current investigations may prove to be useful for designing and fabrication of climate friendly, non-toxic and highly efficient solar cells.

Electron Channeling Contrast Imaging for Beyond Silicon Materials Characterization

2018 ◽  
Author(s):  
Libor Strakos ◽  
Ondrej Machek ◽  
Tomas Vystavel ◽  
Andreas Schulze ◽  
Han Han ◽  
...  
Keyword(s):  
Lattice Mismatch ◽  
Defect Density ◽  
Analytical Techniques ◽  
Device Performance ◽  
Contrast Imaging ◽  
Large Area ◽  
Electron Channeling ◽  
Silicon Materials ◽  
Non Destructive

Abstract As semiconductor devices continue to shrink, novel materials (e.g. (Si)Ge, III/V) are being tested and incorporated to boost device performance. Such materials are difficult to grow on Si wafers without forming crystalline defects due to lattice mismatch. Such defects can decrease or compromise device performance. For this reason, non-destructive, high throughput and reliable analytical techniques are required. In this paper Electron Channeling Contrast Imaging (ECCI), large area mapping and defect detection using deep learning are combined in an analytical workflow for the characterization of the defectivity of “beyond Silicon” materials. Such a workflow addresses the requirements for large areas 10-4 cm2 with defect density down to 104 cm-2.

scholarly journals C-V and I-V characterisation of CdS/CdTe thin film solar cell using defect density model

2021 ◽  
Vol 18 (2) ◽  
pp. 255-270
Author(s):  
Debashish Pal ◽  
Soumee Das
Keyword(s):  
Solar Cell ◽  
Defect Density ◽  
Spectral Response ◽  
Energy Band Diagram ◽  
Density Model ◽  
Device Performance ◽  
Low Frequencies ◽  
Current Voltage ◽  
Capacitance Voltage ◽  
Impurity Doping

This paper presents a detailed study of the current-voltage (I-V) and capacitance-voltage (C-V) measurements made on a CdS/CdTe based solar cell by numerical modeling. Implementation of the simulated cell having a superstrate configuration was done with the help of SCAPS program using defect density model. The I-V characterisation includes window and absorber layer optimisation based on various factors including the impurity doping concentration, thickness and defect density. The energy band diagram, spectral response and currentvoltage plot of the optimised cell configuration are shown. C-V characterisation (Mott-Schottky analysis) of the solar cell is conducted at different low frequencies to determine the flatband potential, carrier concentration and to validate the reliability of the results. The optimum device performance was obtained when the active layer was 2 ?m thick with a doping level of 1?1015/cm3.

Solid Phase Epitaxial Recrystallization of AlN Films on Sapphire (0001): A Novel Substrate Approach for GaN Epitaxy

1999 ◽  
Vol 587 ◽  
Author(s):  
R. D. Vispute ◽  
A. Patel ◽  
R. P. Sharma ◽  
T. Venkatesan ◽  
T. Zheleva ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface Morphology ◽  
Lattice Mismatch ◽  
Defect Density ◽  
Solid Phase ◽  
Substantial Reduction ◽  
Inert Atmosphere ◽  
Buffer Layers ◽  
Large Defect ◽  
Defect Densities

AbstractHigh quality and lattice matched buffer layers are needed for the growth of device quality GaN thin films on sapphire for optoelectronic applications. In this context, we report the fabrication of AlN thin films having low defect densities through a novel process called solid phase epitaxial recrystallization (SPER). In this process, as-grown crystalline AlN thin films, having a large defect concentration (such as threading dislocations due to a large lattice mismatch between AlN and sapphire and low angle grain boundaries), were thermally annealed in an inert atmosphere at various temperatures ranging from 1200-1600° for 30 min. The as-grown and annealed samples were characterized using x-ray diffraction, transmission electron microscopy (TEM), Rutherford backscattering spectroscopy (RBS), atomic force microscopy (AFM) and UV-visible spectroscopy. The ion channeling/RBS and TEM results clearly indicate a substantial reduction in the defect density for the recrystallized AlN films. The surface morphology of the SPER AlN films was smooth with a surface roughness close to the unit cell height. The optical bandgap was sharp as compared to as-grown films, with a bandgap of 6.2 eV. The recrystallized films having smooth surface morphology and low defect densities may be useful for the growth of device quality GaN films on sapphire.

In-Situ Study of NiO Growth on Textured Nickel Tape Using Environmental Scanning Electron Microscope (ESEM) and Hot Stage

2001 ◽  
Vol 7 (S2) ◽  
pp. 1276-1277
Author(s):  
Y. Akin ◽  
R.E. Goddard ◽  
W. Sigmund ◽  
Y.S. Hascicek
Keyword(s):  
Buffer Layer ◽  
Lattice Mismatch ◽  
Sol Gel ◽  
Surface Oxidation ◽  
Dip Coating ◽  
Buffer Layers ◽  
Superconducting Film ◽  
Environmental Scanning ◽  
Cold Rolling And Annealing

Deposition of highly textured ReBa2Cu3O7−δ (RBCO) films on metallic substrates requires a buffer layer to prevent chemical reactions, reduce lattice mismatch between metallic substrate and superconducting film layer, and to prevent diffusion of metal atoms into the superconductor film. Nickel tapes are bi-axially textured by cold rolling and annealing at appropriate temperature (RABiTS) for epitaxial growth of YBa2Cu3O7−δ (YBCO) films. As buffer layers, several oxide thin films and then YBCO were coated on bi-axially textured nickel tapes by dip coating sol-gel process. Biaxially oriented NiO on the cube-textured nickel tape by a process named Surface-Oxidation- Epitaxy (SEO) has been introduced as an alternative buffer layer. in this work we have studied in situ growth of nickel oxide by ESEM and hot stage.Representative cold rolled nickel tape (99.999%) was annealed in an electric furnace under 4% hydrogen-96% argon gas mixture at 1050°C to get bi-axially textured nickel tape.

scholarly journals Selective Area Growth and Structural Characterization of GaN Nanostructures on Si(111) Substrates

Crystals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 366 ◽  
Author(s):  
Alexana Roshko ◽  
Matt Brubaker ◽  
Paul Blanchard ◽  
Todd Harvey ◽  
Kris Bertness
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Lattice Mismatch ◽  
Buffer Layers ◽  
Selective Area Growth ◽  
Gan Nanowires ◽  
Selective Area ◽  
Area Growth ◽  
Eutectic Formation

Selective area growth (SAG) of GaN nanowires and nanowalls on Si(111) substrates with AlN and GaN buffer layers grown by plasma-assisted molecular beam epitaxy was studied. For N-polar samples filling of SAG features increased with decreasing lattice mismatch between the SAG and buffer. Defects related to Al–Si eutectic formation were observed in all samples, irrespective of lattice mismatch and buffer layer polarity. Eutectic related defects in the Si surface caused voids in N-polar samples, but not in metal-polar samples. Likewise, inversion domains were present in N-polar, but not metal-polar samples. The morphology of Ga-polar GaN SAG on nitride buffered Si(111) was similar to that of homoepitaxial GaN SAG.

III-Nitride Growth on Lithium Niobate: A New Substrate Material for Polarity Engineering in III-Nitride Heteroepitaxy

2002 ◽  
Vol 743 ◽  
Author(s):  
W. Alan Doolittle ◽  
Gon Namkoong ◽  
Alexander Carver ◽  
Walter Henderson ◽  
Dieter Jundt ◽  
...  
Keyword(s):  
Lithium Niobate ◽  
Lattice Mismatch ◽  
Substrate Material ◽  
Buffer Layers ◽  
Initial Growth ◽  
Periodically Poled ◽  
Film Adhesion ◽  
Electro Optic ◽  
Bandgap Semiconductors ◽  
Aln Buffer

ABSTRACTHerein, we discuss the use of a novel new substrate for III-Nitride epitaxy, Lithium Niobate. It is shown that Lithium Niobate (LN) has a smaller lattice mismatch to III-Nitrides than sapphire and can be used to control the polarity of III-Nitride films grown by plasma assisted molecular beam epitaxy. Results from initial growth studies are reported including using various nitridation/buffer conditions along with structural and optical characterization. Comparisons of data obtained from GaN and AlN buffer layers are offered and details of the film adhesion dependence on buffer layer conditions is presented. Lateral polarization heterostructures grown on periodically poled LN are also demonstrated. While work is still required to establish the limits of the methods proposed herein, these initial studies offer the promise for mixing III-Nitride semiconductor materials with lithium niobate allowing wide bandgap semiconductors to utilize the acoustic, pyroelectric/ferroelectric, electro-optic, and nonlinear optical properties of this new substrate material as well as the ability to engineer various polarization structures for future devices.

Group III-Sb Metamorphic Buffer on Si for p-Channel all-III-V CMOS: Electrical Properties, Growth and Surface Defects

2015 ◽  
Vol 1790 ◽  
pp. 13-18
Author(s):  
Shun Sasaki ◽  
Shailesh Madisetti ◽  
Vadim Tokranov ◽  
Michael Yakimov ◽  
Makoto Hirayama ◽  
...  
Keyword(s):  
Surface Defects ◽  
Lattice Mismatch ◽  
Chemical Properties ◽  
Antiphase Domain ◽  
Hole Transport ◽  
Heteroepitaxial Growth ◽  
Group Iii ◽  
Similar Chemical ◽  
Unintentional Doping ◽  
P Type

ABSTRACTGroup III-Sb compound semiconductors are promising materials for future CMOS circuits. Especially, In1-xGaxSb is considered as a complimentary p-type channel material to n-type In1-xGaxAs MOSFET due to the superior hole transport properties and similar chemical properties in III-Sb’s to those of InGaAs. The heteroepitaxial growth of In1-xGaxSb on Si substrate has significant advantage for volume fabrication of III-V ICs. However large lattice mismatch between InGaSb and Si results in many growth-related defects (micro twins, threading dislocations and antiphase domain boundaries); these defects also act as deep acceptor levels. Accordingly, unintentional doping in InGaSb films causes additional scattering, increase junction leakages and affects the interface properties. In this paper, we studied the correlations between of defects and hole carrier densities in GaSb and strained In1-xGaxSb quantum well layers by using various designs of metamorphic superlattice buffers.

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