Microcrystalline Germanium Photodetectors

2001 ◽  
Vol 664 ◽  
Author(s):  
M. Krause ◽  
H. Stiebig ◽  
R. Carius ◽  
H. Wagner
Keyword(s):  
Electronic Properties ◽  
Near Infrared ◽  
Short Circuit ◽  
Chemical Vapor ◽  
Short Circuit Current ◽  
Infrared Light ◽  
High Hydrogen ◽  
Sensor Applications ◽  
Hydrogen Dilution ◽  
Structural And Electronic Properties

ABSTRACTFor sensor applications in the detection of near infrared light we have prepared μc-Ge:H by plasma enhanced chemical vapor deposition (PECVD) with a mixture of germane and hydrogen, investigatedits structural and electronic properties and incorporated it into thin pin diodes. In order to ensure microcrystalline growth we had to use high hydrogen dilution. However, only the material prepared with a ratio of germane to hydrogen of 0.2% shows high crystallinity. The optical absorption is remarkably different from c-Ge and exhibits no indication of a direct gap at 0.8eV. When this material is implemented as part of a 110nm thin absorber, a short circuit current of 20mA/cm2 and a quantum efficiency of 15% at a wavelength of 1.1μm are achieved. Higher germane concentrations in hydrogen lead to poor electronic properties due to an increase of the amorphous phase and the short circuit current of the devices deteriorates. As for crystalline germanium photodiodes cooling of the devices is used to overcome the restrictionoriginating from the high free carrier concentration.

scholarly journals Improved efficiency of dye-sensitized solar cells by doping of strontium aluminate phosphor in TiO2 photoelectrode

2015 ◽  
Vol 33 (2) ◽  
pp. 237-241
Author(s):  
Seung Hwangbo ◽  
Jin-Tae Kim ◽  
Kyu-Seog Hwang
Keyword(s):  
Near Infrared ◽  
Spray Deposition ◽  
Short Circuit ◽  
Dye Sensitized Solar Cells ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Infrared Light ◽  
Electrostatic Spray Deposition ◽  
Dye Sensitized ◽  
Near Ultraviolet

AbstractSrAl2O4:Eu2+, Dy3+ phosphor was synthesized by chemical solution route to use as a dopant in TiO2 layer employed as a photoelectrode for down conversion of ultraviolet and near-ultraviolet to visible and near-infrared light in a dye-sensitized solar cell. Nano-crystalline structure of the SrAl2O4:Eu2+, Dy3+ powder was confirmed by X-ray diffraction analysis and field emission scanning electron microscopy. Monitored at 520 nm, SrAl2O4:Eu2+, Dy3+ phosphor showed emission peaks at 460 to 610 nm due to 4f6 4f7 transitions of Eu2+ ions. For the study, SrAl2O4:Eu2+, Dy3+ phosphor-doped TiO2 layer was deposited on fluorine-doped tin oxide coated glass by electrostatic spray deposition. The short circuit current, open circuit voltage, fill factor, and conversion efficiency of the cells were measured. Experimental results revealed that the device efficiency for the SrAl2O4:Eu2+, Dy3+ phosphor-doped TiO2 layer increased to 7.20 %, whereas that of the pure-TiO2 photoelectrode was 4.13 %.

Material Basis of Highly Stable a-Si:H Solar Cells

1996 ◽  
Vol 420 ◽  
Author(s):  
B. Rech ◽  
S. Wieder ◽  
F. Siebke ◽  
C. Beneking ◽  
H. Wagner
Keyword(s):  
Defect Density ◽  
Short Circuit ◽  
Short Circuit Current ◽  
High Hydrogen ◽  
Interface Recombination ◽  
Hydrogen Dilution ◽  
Process Gas ◽  
Current Densities ◽  
Comprehensive Characterization

AbstractWe achieved a stabilized efficiency of 9.2 % after only 8 % relative degradation for an a-Si:H/a-Si:H stacked cell with the top-cell i-layer prepared at 140 °C using a high hydrogen dilution of the silane process gas. From a comprehensive characterization of p-i-n cells and the corresponding i-layer material prepared at 140 °C and 190 °C substrate temperature with different hydrogen dilutions, we conclude that the performance of these pin cells strongly correlates with the material properties of the corresponding i-layers. High fill factors after light soaking are reflected in a good microstructure, high photo-conductivity, and relatively low defect density. Whereas the initial Voc is limited by interface recombination, volume recombination dominates the forward-dark current after light soaking. The stabilized Voc as well as the short-circuit current densities correlate with the optical bandgap of the i-layer.

Structural and Electronic Properties of Hydrogenated Nanocrystalline Silicon Films Made with Hydrogen Dilution Profiling Technique

2005 ◽  
Vol 862 ◽  
Author(s):  
Keda Wang ◽  
Daxing Han ◽  
D. L. Williamson ◽  
Brittany Huie ◽  
J. R. Weinberg-Wolf ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Volume Fraction ◽  
Nanocrystalline Silicon ◽  
Growth Direction ◽  
Structure Evolution ◽  
Excitation Wavelength ◽  
Initial Growth ◽  
High Hydrogen ◽  
Hydrogen Dilution ◽  
Structural And Electronic Properties

AbstractWe used X-ray diffraction (XRD), Raman scattering and photoluminescence (PL) spectroscopy to characterize structural and electronic properties of nc-Si:H films made with different hydrogen dilution ratios and hydrogen dilution profiling with continuously reduced hydrogen dilution during the deposition. The XRD results show that the crystalline volume fraction (fc) is in the range of 60-70% with grain size of 22-26 nm for the nc-Si:H films studied. Comparing the sample made using hydrogen dilution profiling to that with constant hydrogen dilution, the hydrogen dilution profiling promotes the (220) preferential orientation due to a very high hydrogen dilution in the initial growth. The Raman results show that the fc is in the range of 60-90%, depending on the sample and excitation wavelength. For the samples with constant hydrogen dilution, the fc measured by Raman increases along the growth direction. The hydrogen dilution profiling reverses this trend, which affirms that the hydrogen profiling controls the nanocrystalline structure evolution along the growth direction. The PL results show only one peak around 0.8-0.9 eV for the samples made with constant hydrogen dilution, but an additional peak at 1.4 eV appears in the sample made with the hydrogen dilution profiling.

Evolution of Structural and Electronic Properties in Boron-doped Nanocrystalline Silicon Thin Films

2007 ◽  
Vol 989 ◽  
Author(s):  
Hyun Jung Lee ◽  
Andrei Sazonov ◽  
Arokia Nathan
Keyword(s):  
Electronic Properties ◽  
Chemical Vapor ◽  
Boron Doping ◽  
Nanocrystalline Silicon ◽  
Dark Conductivity ◽  
Crystalline Fraction ◽  
Silicon Thin Films ◽  
Boron Doped ◽  
Structural And Electronic Properties ◽  
Effective Mobility

AbstractWe report on the boron-doping dependence of the structural and electronic properties in nanocrystalline silicon (nc-Si:H) films directly deposited by plasma- enhanced chemical vapor deposition (PECVD). The crystallinity, micro-structure, and dark conductivity of the films were investigated by gradually varying the ratio of trimethylboron [B(CH3)3 or TMB] to silane (SiH4) from 0.1 to 2 %. It was found that the low level of boron doping (< 0.2 %) first compensated the nc-Si:H material which demonstrates slightly n-type properties. As the doping increased up to 0.5 %, the maximum dark conductivity (ód) of 1.11 S/cm was obtained while high crystalline fraction (Xc) of the films (over 70 %) was maintained. However, further increase in a TMB-to-SiH4 ratio reduced ód to the order of 10-7 S/cm due to a phase transition of the films from nanocrystalline to amorphous, which was indicated by Raman spectra measurements.P-channel nc-Si:H thin film transistors (TFTs) with top gate and staggered source/drain contacts were fabricated using the developed p+ nc-Si:H layer. The fabricated TFT exhibits a threshold voltage (VTp) of -26.2 V and field effective mobility of holes (μp) of 0.24 cm2/V·s.

scholarly journals Improvement of Exciton Collection and Light-Harvesting Range in Ternary Blend Polymer Solar Cells Based on Two Non-Fullerene Acceptors

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 241 ◽  
Author(s):  
Yanbin Wang ◽  
Changlong Zhuang ◽  
Yawen Fang ◽  
Hyung Do Kim ◽  
Huang Yu ◽  
...  
Keyword(s):  
Near Infrared ◽  
Polymer Solar Cells ◽  
Short Circuit ◽  
Weight Ratio ◽  
Fullerene Molecule ◽  
Short Circuit Current ◽  
Ternary Blend ◽  
Binary Blend ◽  
Efficient Energy Transfer ◽  
Near Ir

A non-fullerene molecule named Y6 was incorporated into a binary blend of PBDB-T and IT-M to further enhance photon harvesting in the near-infrared (near-IR) region. Compared with PBDB-T/IT-M binary blend devices, PBDB-T/IT-M/Y6 ternary blend devices exhibited an improved short-circuit current density (JSC) from 15.34 to 19.09 mA cm−2. As a result, the power conversion efficiency (PCE) increased from 10.65% to 12.50%. With an increasing weight ratio of Y6, the external quantum efficiency (EQE) was enhanced at around 825 nm, which is ascribed to the absorption of Y6. At the same time, EQE was also enhanced at around 600–700 nm, which is ascribed to the absorption of IT-M, although the optical absorption intensity of IT-M decreased with increasing weight ratio of Y6. This is because of the efficient energy transfer from IT-M to Y6, which can collect the IT-M exciton lost in the PBDB-T/IT-M binary blend. Interestingly, the EQE spectra of PBDB-T/IT-M/Y6 ternary blend devices were not only increased but also red-shifted in the near-IR region with increasing weight ratio of Y6. This finding suggests that the absorption spectrum of Y6 is dependent on the weight ratio of Y6, which is probably due to different aggregation states depending on the weight ratio. This aggregate property of Y6 was also studied in terms of surface energy.

Gallium Nitride for Nuclear Batteries

2011 ◽  
Vol 343-344 ◽  
pp. 56-61 ◽  
Author(s):  
Min Lu ◽  
Guo Wang ◽  
Chang Sheng Yao
Keyword(s):  
Gallium Nitride ◽  
Collection Efficiency ◽  
Short Circuit ◽  
Chemical Vapor ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Dead Layer ◽  
Pin Diodes ◽  
Charge Collection Efficiency ◽  
Nuclear Batteries

Gallium Nitride (GaN) PIN betavoltaic nuclear batteries (GB) are demonstrated in our work for the first time. GaN films are grown on sapphire substrates by metalorganic chemical vapor deposition (MOCVD), and then GaN PIN diodes are fabricated by normal micro-fabrication process. Nickel with mass number of 63 (63Ni), which emits β particles, is loaded on the GaN PIN diodes to achieve GB. Current-Voltage (I-V) characteristics shows that the GaN PIN diodes have leakage current of 18 pA at -10V due to consummate fabrication processes, and the open circuit voltage of the GB is estimated about 0.14 V and the short circuit current density is 89.2nAcm-2 . The relative limited performance of the GB is due to thick dead layer and strong backscattering of β particles, Which lead to less energy deposition in GB. However, the conversion efficiency of 1.6% and charge collection efficiency (CCE) of 100% for the GB have been obtained. Therefore, the output power of the GB are expected to greatly increase with thin dead layer and structural surface weakening the backscattering.

Silicon nanowires solar cell

2011 ◽  
Vol 1305 ◽  
Author(s):  
Xiaobing Xie ◽  
Xiangbo Zeng ◽  
Wenjie Yao ◽  
Ping Yang ◽  
Shiyong Liu ◽  
...  
Keyword(s):  
Solar Cell ◽  
Silicon Nanowires ◽  
Short Circuit ◽  
Nanowire Array ◽  
Chemical Vapor ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Type Layer ◽  
Si Nanowire Array

ABSTRACTWe made an amorphous-silicon (a-Si) solar cell with a nanowire-array structure on stainless steel(SS) by plasma enhanced chemical vapor (PECVD) deposition. This nanowire structure has an n-type Si nanowire array in which a-Si intrinsic layer and p type layer are sequentially grown on the surface of the nanowire. The highest open-circuit voltage (Voc) and short-circuit current density (Jsc) for AM 1.5 illumination were 620 mV and 13.4 mA/cm2, respectively at a maximum power conversion efficiency of 3.57%.

scholarly journals Epitaxial Growth of Germanium on Silicon for Light Emitters

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Chengzhao Chen ◽  
Cheng Li ◽  
Shihao Huang ◽  
Yuanyu Zheng ◽  
Hongkai Lai ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Near Infrared ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
Sige Layer ◽  
Infrared Light ◽  
Multiple Quantum ◽  
Light Emitters ◽  
Large Lattice ◽  
Large Lattice Mismatch

This paper describes the role of Ge as an enabler for light emitters on a Si platform. In spite of the large lattice mismatch of ~4.2% between Ge and Si, high-quality Ge layers can be epitaxially grown on Si by ultrahigh-vacuum chemical vapor deposition. Applications of the Ge layers to near-infrared light emitters with various structures are reviewed, including the tensile-strained Ge epilayer, the Ge epilayer with a delta-doping SiGe layer, and the Ge/SiGe multiple quantum wells on Si. The fundamentals of photoluminescence physics in the different Ge structures are discussed briefly.

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