scholarly journals H2-Dilution vs. Buffer Layers for Increased Voc

1996 ◽  
Vol 420 ◽  
Author(s):  
R. Platz ◽  
D. Fischer ◽  
C. Hof ◽  
S. Dubail ◽  
J. Meier ◽  
...  
Keyword(s):  
Substrate Temperature ◽  
Buffer Layer ◽  
Light Absorption ◽  
Boron Doping ◽  
Buffer Layers ◽  
Tandem Cell ◽  
Hydrogen Dilution ◽  
Lower Temperature ◽  
The Stability ◽  
Lower Substrate Temperature

AbstractHydrogen dilution and buffer layers, as two ways to obtain higher Voc values in a-Si:H p-i-n solar cells, are directly compared in the present study. Special emphasis is laid on stability against light soaking. H2-dilution in combination with lower substrate temperature yields higher Voc values and better stability as compared to buffer layers. However, light absorption is decreased due to the increased gap in H2-diluted cells. The stability of buffer layer cells can remarkably be ameliorated by boron doping and H2-dilution of the a-SiC:H buffer layer. However, stabilized efficiency is higher for optimized diluted cells than for cells with a buffer layer. An a-Si/a-Si stacked cell with a graded dilution for both cells yielded 10% initial efficiency with 17% relative degradation. Diluted a-Si:H cells at lower temperature become specially interesting in combination with a microcrystalline bottom cell. For such a “micromorph” tandem cell we obtained 11.4% initial efficiency.

scholarly journals VHF-Deposited a-SiC:H Alloys for High-Bandgap Solar Cells: Combining High Voc and Reasonable Stability

1995 ◽  
Vol 377 ◽  
Author(s):  
R. Platz ◽  
D. Fischer ◽  
A. Shah
Keyword(s):  
Solar Cells ◽  
Buffer Layer ◽  
Material Properties ◽  
Cell Performance ◽  
Buffer Layers ◽  
Hydrogen Dilution ◽  
The Stability

ABSTRACTThe material properties of a-SiC:H alloys deposited by VHFGD are studied, with a special emphasis on the effect of hydrogen dilution of the plasma on layer quality. By incorporating these layers into p-i-n solar cells the authors compare layer properties and cell performance. Special attention is paid to the stability of the solar cells against light soaking. Furthermore, the authors show that the insertion of a buffer layer can, also in the case of entirely a-SiC:H cells, lead to a substantial increase of Voc. A reasonable stability of these cells is maintained by an appropriate doping of the buffer layers.

The Effects of Various Substrate Temperature of Bi2O3 Buffer Layer on SBT (SrBi2Ta2O9) Thin Films Deposited by R.F. Magnetron Sputtering

2008 ◽  
Vol 569 ◽  
pp. 137-140
Author(s):  
Ji Eon Yoon ◽  
Won Hyo Cha ◽  
Dong Hyun Hwang ◽  
Chul Su Lee ◽  
In Seok Lee ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Substrate Temperature ◽  
Buffer Layer ◽  
Ferroelectric Properties ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lower Temperature ◽  
Temperature Crystallization

The SBT(SrBi2Ta2O9) thin films with Bi2O3 buffer layer were deposited on Pt/Ti/SiO2/Si substrate by R.F. magnetron sputtering method in order to improve the ferroelectric characteristics. In SBT thin films, the deficiency of bismuth due to its volatility during the process results in an obvious non stoichiometry of the films and the presence of secondary phases. Bi2O3 buffer layer was found to be effective to achieve lower temperature crystallization and improve ferroelectric properties of SBT thin films. Ferroelectric properties and crystallinities of SBT thin films with various substrate temperature of Bi2O3 buffer layer were observed, using X-Ray Diffraction (XRD), Precision LC (Radient Technologies. Inc.) and GDS (glow discharge spectrometer).

scholarly journals Comparison of VHF, RF and Dc Plasma Excitation for a-Si:H Deposition with Hydrogen Dilution

1998 ◽  
Vol 507 ◽  
Author(s):  
R. Platz ◽  
C. Hof ◽  
S. Wieder ◽  
B. Rech ◽  
D. Fischer ◽  
...  
Keyword(s):  
Growth Rate ◽  
Substrate Temperature ◽  
Transport Properties ◽  
Electronic Transport ◽  
Chemical Vapor ◽  
Dilution Ratio ◽  
Electronic Transport Properties ◽  
Optical Gap ◽  
Hydrogen Dilution ◽  
The Stability

ABSTRACTA comparative study of DC, RF and VHF excitation for the plasma enhanced chemical vapor deposition (PECVD) of intrinsic layers of a-Si:H is presented, with special emphasis on the effects of hydrogen dilution. Growth rates at comparable plasma power, for substrate temperatures between 100°C and 300°C and for various H2 dilution ratios are presented, along with optical bandgap, H content, and electronic transport properties in the light-soaked state.H2 strongly reduces the growth rate for all techniques. The growth rate for the highest H2 dilution ratio is approximately four times higher for VHF than for DC or RF excitation. In all three cases increasing the substrate temperature reduces the optical gap and the H content CH. Raising the substrate temperature slightly enhances the stability of undiluted films. H2 dilution increases the optical gap for all three techniques. The H content of RF- and VHF-deposited samples increases with increasing H2 dilution ratio, while in DC deposition it produces an initial drop of the H content, followed by an increase.In all three cases, H2 dilution improves the electronic transport properties of the material by roughly a factor of two. The gain in stability is most pronounced for relatively small dilution; in the case of DC deposition, too strong a dilution even has an adverse effect on stability.

Modelling and calculation of characteristic parameters of the active and buffer layers in organic solar cell

2020 ◽  
Vol 16 ◽  
Author(s):  
Minh Duc Tran ◽  
Nguyen Dinh Lam
Keyword(s):  
Zinc Oxide ◽  
Solar Cell ◽  
Buffer Layer ◽  
Active Layer ◽  
Light Absorption ◽  
Organic Solar Cell ◽  
Buffer Layers ◽  
Electron Transport Layer ◽  
Characteristic Parameters ◽  
Charge Mobility

Background: The active layer not only must have a strong light absorption in the visible spectrum, but must also be sufficient for charge carrier transport to the electrodes. Electrons in conducting polymer transport by hopping between different energy levels, resulted in much lower charge mobility. Therefore, the thickness of active layer must be limited so the separated charge can reach the corresponding electrodes without recombination. However, thin active layer has weaker light absorption, resulting in the low photogenerated current in organic solar cell devices. Furthermore, buffer layers usually have high charge mobility, which in turn would enhance the transportation of charge from the active layer to electrodes. Metal oxides have been studied to be used as cathode buffer layer such as titanium dioxide (TiO2), zinc oxide (ZnO), etc. Objective: In this work, behaviors of the photon-electrical characteristics with variation in thickness of the active (poly(3-hexylthiophene-2,5-diyl) and phenyl-C61 butyric acid methyl ester blend) and buffer (zinc oxide) layers were investigated. Method: The influences of the thickness of the active and buffer layers on characteristic parameters of organic solar cells were investigated by solving the drift and diffusion equation with the photogenerated current given by Hetch equation. Results: The optimum thickness was obtained around 100 nm and below 10 nm for the active and the ZnO buffer layers, respectively. Conclusion: Thinner active layer resulted in lower photocurrent due to poor light absorption while at 150 nm thick and above, PCE of the device reduced rapidly because of high recombination rate of photogenerated electron-hole pairs. ZnO buffer layer was used as an electron transport layer and a hole blocking layer in order to improve the cell’s performance. The addition of ZnO enhanced the PCE up to 2.48 times higher than conventional device.

Structural and Electrical Properties of Y2O3 Buffer Layer Prepared by Two Step Process

2001 ◽  
Vol 666 ◽  
Author(s):  
Dong-Gun Lim ◽  
Bum-Sik Jang ◽  
Sang-Il Moon ◽  
Dong-Min Jang ◽  
Jinhee Heo ◽  
...  
Keyword(s):  
Substrate Temperature ◽  
Partial Pressure ◽  
Buffer Layer ◽  
Film Growth ◽  
Lattice Mismatch ◽  
Metal Layer ◽  
Buffer Layers ◽  
Step Process ◽  
Structural And Electrical Properties ◽  
Semiconductor Type

ABSTRACTIn this paper we investigated a feasibility of Y2O3 films as a buffer layer of MFIS (metal ferroelectric insulator semiconductor) type capacitor. Buffer layers were prepared by two-step process of a low temperature film growth and subsequent RTA treatment. Investigated parameters are given as substrate temperature, O2 partial pressure, post-annealing temperature, and suppression method of interfacial SiO2layer generation. By employing an ultra thin Y pre-metal layer, unwanted SiO2 layer generation was successfully suppressed at an interface between the buffer layer and Si substrate. By using two-step process, we improved the leakage current density of Y2O3 films by 2 orders and the Dit as low as 8.72×1010 cm−2eV−1. For a substrate temperature above 400°C and O2 partial pressure of 20%, we observed cubic Y2O3 phase domination in XRD spectra. We achieved 1.75% lattice mismatch between Y2O3 film and silicon substrate. Y2O3 buffer layer for a single transistor FRAM exhibited optimal properties when it was grown at 400°C with 20% O2 partial pressure then RTA treatment at 900°C in oxygen ambient.

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.

Characterization of Microcrystalline Transition from Amorphous Silicon as a Function of Hydrogen Dilution and Substrate Temperature of Hot-wire CVD

2002 ◽  
Vol 715 ◽  
Author(s):  
Keda Wang ◽  
Haoyue Zhang ◽  
Jian Zhang ◽  
Jessica M. Owens ◽  
Jennifer Weinberg-Wolf ◽  
...  
Keyword(s):  
Substrate Temperature ◽  
Sudden Change ◽  
Chemical Vapor ◽  
Threshold Value ◽  
Ir Absorption ◽  
Sudden Increase ◽  
Hot Wire ◽  
Hydrogen Dilution ◽  
Integral Absorption ◽  
Two Peaks

Abstracta-Si:H films were prepared by hot wire chemical vapor deposition. One group was deposited at a substrate temperature of Ts=250°C with varied hydrogen-dilution ratio, 0<R<10; the other group was deposited with fixed R=3 but a varied Ts from 150 to 550°C. IR, Raman and PL spectra were studied. The Raman results indicate that there is a threshold value for the microstructure transition from a- to μc-Si. The threshold is found to be R ≈ 2 at Ts = 250°C and Ts ≈ 200°C at R=3. The IR absorption of Si-H at 640 cm-1 was used to calculate the hydrogen content, CH. CH decreased monotonically when either R or Ts increased. The Si-H stretching mode contains two peaks at 2000 and 2090 cm-1. The ratio of the integral absorption peaks I2090/(I2090+I2090) showed a sudden increase at the threshold of microcrystallinity. At the same threshold, the PL features also indicate a sudden change from a- to μc-Si., i.e. the low energy PL band becomes dominant and the PL total intensity decreases. We attribute the above IR and PL changes to the contribution of microcrystallinity, especially the c-Si gain-boundaries.

Effects of the Sputtering Time of AlN Buffer Layer on the Quality of ZnO Thin Films

2014 ◽  
Vol 881-883 ◽  
pp. 1117-1121 ◽  
Author(s):  
Xiang Min Zhao
Keyword(s):  
Thin Films ◽  
Buffer Layer ◽  
Rf Magnetron Sputtering ◽  
Buffer Layers ◽  
Zno Thin Films ◽  
Zno Films ◽  
Si Substrates ◽  
Atomic Force ◽  
Structure Morphology ◽  
Aln Buffer

ZnO thin films with different thickness (the sputtering time of AlN buffer layers was 0 min, 30 min,60 min, and 90 min, respectively) were prepared on Si substrates using radio frequency (RF) magnetron sputtering system.X-ray diffraction (XRD), atomic force microscope (AFM), Hall measurements setup (Hall) were used to analyze the structure, morphology and electrical properties of ZnO films.The results show that growth are still preferred (002) orientation of ZnO thin films with different sputtering time of AlN buffer layer,and for the better growth of ZnO films, the optimal sputtering time is 60 min.

The Influence of Growth Temperature on Oxygen Concentration in GaN Buffer Layer

2008 ◽  
Vol 1068 ◽  
Author(s):  
Ewa Dumiszewska ◽  
Wlodek Strupinski ◽  
Piotr Caban ◽  
Marek Wesolowski ◽  
Dariusz Lenkiewicz ◽  
...  
Keyword(s):  
High Temperature ◽  
Buffer Layer ◽  
Oxygen Concentration ◽  
Growth Temperature ◽  
Low Temperatures ◽  
Buffer Layers ◽  
Crystalline Quality ◽  
Temperature Growth ◽  
Gan Buffer Layer

ABSTRACTThe influence of growth temperature on oxygen incorporation into GaN epitaxial layers was studied. GaN layers deposited at low temperatures were characterized by much higher oxygen concentration than those deposited at high temperature typically used for epitaxial growth. GaN buffer layers (HT GaN) about 1 μm thick were deposited on GaN nucleation layers (NL) with various thicknesses. The influence of NL thickness on crystalline quality and oxygen concentration of HT GaN layers were studied using RBS and SIMS. With increasing thickness of NL the crystalline quality of GaN buffer layers deteriorates and the oxygen concentration increases. It was observed that oxygen atoms incorporated at low temperature in NL diffuse into GaN buffer layer during high temperature growth as a consequence GaN NL is the source for unintentional oxygen doping.

Sign in / Sign up

Export Citation Format

Share Document