scholarly journals H Out-Diffusion and Device Performance in n-i-p Solar Cells Utilizing High Temperature Hot Wire a-Si:H i-Layers

1998 ◽  
Vol 507 ◽  
Author(s):  
A. H. Mahan ◽  
R. C. Reedy ◽  
E. Iwaniczko ◽  
Q. Wang ◽  
B. P. Nelson ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Buffer Layer ◽  
Diffusion Coefficients ◽  
Chemical Potential ◽  
Secondary Ion Mass Spectrometry ◽  
Buffer Layers ◽  
Device Performance ◽  
Hot Wire ◽  
Defective Layer

ABSTRACTHydrogen out-diffusion from the n/i interface region plays a major role in controlling the fill factor (FF) and resultant efficiency of n-i-p a-Si:H devices, with the i-layer deposited at high substrate temperatures by the hot wire technique. Modeling calculations show that a thin, highly defective layer at this interface, perhaps caused by significant H out-diffusion and incomplete lattice reconstruction, results in sharply lower device FF's due to the large voltage dropped across this defective layer. One approach to this problem is to introduce trace dopant tailing to ‘compensate’ these defects, but the resultant cells exhibit a poor red response. A second approach involves the addition of buffer layers designed to retard this out-diffusion. We find that an increased H content, either in the n-layer or a thin intrinsic low temperature buffer layer, does not significantly retard this out-diffusion, as observed by secondary ion mass spectrometry (SIMS) H profiles on devices. All these devices have a defect-rich i-layer region near the n/i interface and a poor device efficiency. However, if this low temperature buffer layer is thick enough, the outdiffusion is minimized, yielding nearly flat H profiles and a much improved device performance. We discuss this behavior in the context of the H chemical potentials and H diffusion coefficients in the high temperature, buffer, n-, and stainless steel (SS) substrate layers. The chemical potential differences between the layers control the direction of the H flow and the respective diffusion coefficients, which depend upon many factors such as the local electronic Fermi energy and the extent of the H depletion, determine the rate. Finally, we report a 9.8% initial active area device, fabricated at 16Å/s, using the insights obtained in this study.

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.

Initial Buffer Layers on the Growth of InGaP on Si by MBE

1996 ◽  
Vol 441 ◽  
Author(s):  
H. Kawanami ◽  
S. Ghosh ◽  
I. Sakata ◽  
T. Sekigawa
Keyword(s):  
High Temperature ◽  
Surface Structure ◽  
Buffer Layer ◽  
Molecular Beam ◽  
Single Domain ◽  
Buffer Layers ◽  
Structure Control ◽  
Si Substrates ◽  
Direct Growth ◽  
Initial Buffer

AbstractSingle domain InxGa(1-x)P (x=0.3) films were successfully grown on Si(001) misoriented substrates by molecular beam epitaxy with a solid phosphorous source. The effects of interfacial buffer layers such as InGaP (i.e. direct growth without buffer layer), GaP, AlP, and GaAs were examined. Also a Si epitaxial buffer layer was tried to control the Si surface structure. Mirror like surfaces were obtained for all films with RHEED patterns of (2×1) single domain surface structure. PL intensities for all films indicated almost the same values except for the films with a Si epitaxial buffer layer. The films with a Si epitaxial buffer layer had almost three times larger PL intensities than the films without Si epitaxial buffer layer. The results suggest incomplete cleaning of the Si surface by the high temperature (1000 °C) treatment and possibility of surface structure control for Si substrates by a Si epitaxial buffer layer.

Preparation of PbZrxTi1−xO3 Films on Si Substrates Using SrTiO3 Buffer Layers

1994 ◽  
Vol 361 ◽  
Author(s):  
Eisuke Tokumitsu ◽  
Kensuke Itani ◽  
Bum-Ki Moon ◽  
Hiroshi Ishiwara
Keyword(s):  
Buffer Layer ◽  
Secondary Ion Mass Spectrometry ◽  
Sol Gel ◽  
Buffer Layers ◽  
Si Substrates ◽  
Pzt Film ◽  
Pzt Films ◽  
Evaporation Technique ◽  
Gel Technique ◽  
Secondary Ion

ABSTRACTWe report the preparation of PbZrxTi1−xO3 (PZT) films on Si substrates with a SrTiO3 (STO) buffer layer. STO buffer layers and PZT films were formed on Si substrates by the electron-beam assisted vacuum evaporation technique and sol-gel technique, respectively. By evaporating a thin (8nm) metal Sr layer prior to the STO deposition, which deoxidizes the SiO2 layer at the Si surface, (100)- and (111)-oriented STO thin films can be grown on Si(100) and (111) substrates, respectively. It is shown that a strongly (100)-oriented PZT film is grown on STO(100)/Si(100), whereas a strongly (111)-oriented PZT film is obtained on STO(111)/Si(111). It is also found that the STO buffer layer remains intact even after the PZT deposition. Secondary ion mass spectrometry (SIMS) analysis showed that the STO barrier layer was effective in preventing diffusion of Pb into the Si substrate.

scholarly journals High-Temperature Atomic Layer Deposition of GaN on 1D Nanostructures

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2434
Author(s):  
Aaron J. Austin ◽  
Elena Echeverria ◽  
Phadindra Wagle ◽  
Punya Mainali ◽  
Derek Meyers ◽  
...  
Keyword(s):  
Thin Films ◽  
High Temperature ◽  
Atomic Layer Deposition ◽  
Buffer Layer ◽  
Atomic Layer ◽  
Buffer Layers ◽  
X Ray ◽  
1D Nanostructures ◽  
Layer Deposition ◽  
Silica Nanosprings

Silica nanosprings (NS) were coated with gallium nitride (GaN) by high-temperature atomic layer deposition. The deposition temperature was 800 °C using trimethylgallium (TMG) as the Ga source and ammonia (NH3) as the reactive nitrogen source. The growth of GaN on silica nanosprings was compared with deposition of GaN thin films to elucidate the growth properties. The effects of buffer layers of aluminum nitride (AlN) and aluminum oxide (Al2O3) on the stoichiometry, chemical bonding, and morphology of GaN thin films were determined with X-ray photoelectron spectroscopy (XPS), high-resolution x-ray diffraction (HRXRD), and atomic force microscopy (AFM). Scanning and transmission electron microscopy of coated silica nanosprings were compared with corresponding data for the GaN thin films. As grown, GaN on NS is conformal and amorphous. Upon introducing buffer layers of Al2O3 or AlN or combinations thereof, GaN is nanocrystalline with an average crystallite size of 11.5 ± 0.5 nm. The electrical properties of the GaN coated NS depends on whether or not a buffer layer is present and the choice of the buffer layer. In addition, the IV curves of GaN coated NS and the thin films (TF) with corresponding buffer layers, or lack thereof, show similar characteristic features, which supports the conclusion that atomic layer deposition (ALD) of GaN thin films with and without buffer layers translates to 1D nanostructures.

Low temperature aqueous solution-processed Li doped ZnO buffer layers for high performance inverted organic solar cells

2016 ◽  
Vol 4 (25) ◽  
pp. 6169-6175 ◽  
Author(s):  
Zhenhua Lin ◽  
Jingjing Chang ◽  
Chunfu Zhang ◽  
Jincheng Zhang ◽  
Jishan Wu ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Solar Cells ◽  
Low Temperature ◽  
Buffer Layer ◽  
Organic Solar Cells ◽  
High Performance ◽  
Photovoltaic Performance ◽  
Buffer Layers ◽  
Solution Processed ◽  
Doped Zno

An enhanced photovoltaic performance is achieved by employing a lithium doped ZnO layer as the electron buffer layer for organic solar cells.

Effects of the Nitridation Process of (0001) Sapphire on Crystalline Quality of InN Grown by RF-MBE

2004 ◽  
Vol 831 ◽  
Author(s):  
Daisuke Muto ◽  
Ryotaro Yoneda ◽  
Hiroyuki Naoi ◽  
Masahito Kurouchi ◽  
Tsutomu Araki ◽  
...  
Keyword(s):  
Low Temperature ◽  
Buffer Layer ◽  
Buffer Layers ◽  
Crystalline Quality ◽  
Constant Independent ◽  
Nitrogen Flux ◽  
Sapphire Substrates ◽  
Nitridation Process ◽  
Flux Modulation

ABSTRACTThe effects of the nitridation process of (0001) sapphire on crystalline quality of InN were clearly demonstrated. The InN films were grown on NFM (nitrogen flux modulation) HT-InN or LT-InN buffer layers, which had been deposited on nitridated sapphire substrates. We found that low-temperature nitridation of sapphire is effective in improving the tilt distribution of InN films. Whereas the twist distribution remained narrow and almost constant, independent of nitridation conditions, when LT-InN buffer layers were used. The XRC-FWHM value of 54 arcsec for (0002) InN, the lowest reported to date, was achieved by using the LT-InN buffer layer and sapphire nitridation at 300°C for 3 hours.

scholarly journals Growth Of High Quality GaN Thin Films By MBE On Intermediate-temperature Buffer Layers

2000 ◽  
Vol 5 (1) ◽  
Author(s):  
W.K. Fong ◽  
C. F. Zhu ◽  
B. H. Leung ◽  
Charles Surya
Keyword(s):  
Low Temperature ◽  
Buffer Layer ◽  
Electron Mobility ◽  
Unique Feature ◽  
Growth Conditions ◽  
Intermediate Temperature ◽  
Buffer Layers ◽  
Rf Plasma ◽  
Epitaxial Layers ◽  
High Quality

We report the growth of high quality GaN epitaxial layers by rf-plasma MBE. The unique feature of our growth process is that the GaN epitaxial layers are grown on top of a double layer that consists of an intermediate-temperature buffer layer (ITBL), which is grown at 690°C and a conventional low-temperature buffer layer deposited at 500°C. It is observed that the electron mobility increases steadily with the thickness of the ITBL, which peaks at 377 cm2V−1s−1 for an ITBL thickness of 800 nm. The PL also demonstrated systematic improvements with the thickness of the ITBL. Our analyses of the mobility and the photoluminescence characteristics demonstrate that the utilization of an ITBL in addition to the conventional low-temperature buffer layer leads to the relaxation of residual strain within the material resulting in improvement in the optoelectronic properties of the films. A maximum electron mobility of 430 cm2V−1s−1 can be obtained using this technique and further optimizing the growth conditions for the low-temperature buffer layer.

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