Carrier Transport and Photogeneration in Amorphous Silicon / Crystalline Silicon Heterojunctions with i/n and p/n Interfaces

2000 ◽  
Vol 609 ◽  
Author(s):  
Yu. Vygranenko ◽  
M. Fernandes ◽  
C. Nunes Carvalho ◽  
G. Lavareda ◽  
P. Louro ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Carrier Transport ◽  
Crystalline Silicon ◽  
Collection Efficiency ◽  
Spectral Response ◽  
Chemical Vapour ◽  
Amorphous Film ◽  
Amorphous Layer ◽  
Hydrogen Treatment ◽  
Internal Gain

ABSTRACTAmorphous hydrogenated silicon films deposited by Plasma Enhanced Chemical Vapour Deposition (PE-CVD) using standard rf-glow discharge at 13.56 MHz were used to produce amorphous silicon heterostructures. Junction properties were studied from current-voltage (IV), capacitance-voltage (C-V) and spectral response measurements. The photosensitivity of these structures was investigated for different amorphous film thicknesses and different applied bias voltages. It was shown that the output device characteristics could be improved by plasma hydrogen treatment before the deposition of the amorphous layer. The results show that ITO/a-Si:H/c-Si structures present high internal gain in the visible infra-red region and high collection efficiency in the blue range. They can be used as visible/near-IR photodiodes or for current amplifications proposes.

Photogeneration and Carrier Transport in Amorphous Silicon/Crystalline Silicon Devices

1997 ◽  
Vol 467 ◽  
Author(s):  
B. Jagannathan ◽  
W. A. Anderson
Keyword(s):  
Amorphous Silicon ◽  
Carrier Transport ◽  
Crystalline Silicon ◽  
Plasma Deposition ◽  
Spectral Response ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Silicon Devices

ABSTRACTHydrogenated amorphous silicon (a-Si:H)/ crystalline silicon (c-Si) type heterodiodes in solar cell structures have been studied by rf glow discharge, dc magnetron sputtering, and a remote plasma deposition of a-Si:H onto p type c-Si. Carrier transport and photogeneration in such structures have been investigated by current-voltage-temperature, thermally stimulated capacitance (TSCAP), and spectral response experiments. Dark carrier conduction is found to be a combination of tunneling and interface recombination, but is dominated by either one depending on the deposition/sputtering conditions. The conditions investigated include energy of the plasma species, type of plasma cleaning, and substrate preparation techniques. For each of the conditions, the trap type, energy and concentration have been identified by TSCAP. Solar cells fabricated by the optimized fabrication scheme routinely yield 10.5% efficient devices having a short circuit current density (Jsc) of 30 mA/cm2, a open circuit voltage of 0.55 volts and a fill factor (FF) of 0.64, without an AR coating, over 0.3 cm2 area.

Large Area Flexible Amorphous Silicon Position Sensitive Detectors

2000 ◽  
Vol 609 ◽  
Author(s):  
Elvira M.C. Fortunato ◽  
Donatello Brida ◽  
Isabel M.M. Ferreira ◽  
H. M.B. Åguas ◽  
Patrícia Nunes ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Spectral Response ◽  
Chemical Vapour ◽  
Open Circuit ◽  
Large Area ◽  
Force Microscopy ◽  
Glass Substrates ◽  
Chemical Vapour Deposition Technique ◽  
Position Sensitive ◽  
Position Sensitive Detectors

ABSTRACTLarge area thin film position sensitive detectors based on amorphous silicon technology have been prepared on polyimide substrates using the conventional plasma enhanced chemical vapour deposition technique. The sensors have been characterised by spectral response, illuminated I-V characteristics and position detectability measurements. The obtained one dimensional position sensors with 5 mm wide and 60 mm long present a maximum spectral response at 600 nm, an open circuit voltage of 0.6 V and a position detectability with a correlation of 0.9989 associated to a standard deviation of 1×10−2, comparable to those ones produced on glass substrates. The surface of the sensors at each stage of fabrication was investigated by Atomic Force Microscopy.

Seed-Induced Crystallization of Amorphous Silicon for the Formation of Large-Grain Poly-Crystalline Silicon

2010 ◽  
Author(s):  
Jason Trask ◽  
Lin Cui ◽  
Andrew J. Wagner ◽  
K. Andre Mkhoyan ◽  
Uwe Kortshagen
Keyword(s):  
Amorphous Silicon ◽  
Crystalline Silicon ◽  
Amorphous Film ◽  
Average Crystallite Size ◽  
Dark Conductivity ◽  
Film Deposition ◽  
Grain Structure ◽  
Crystallization Time ◽  
Silicon Thin Films ◽  
Initial Seed

A new method for reducing crystallization time of hydrogenated amorphous silicon thin films and more successfully controlling grain structure has been studied through seeding of the bulk matrix with nanocrystallites during film deposition. Films were deposited by a system in which crystallites and amorphous film were synthesized in separate RF-powered plasmas. Average crystallite size was confirmed to be 20 to 50 nm via TEM imaging. Several films with various initial crystallite population densities were produced, and their crystallization kinetics were studied via Raman spectroscopy throughout a staged annealing process. Seeded films consistently displayed a characteristic crystallization time less than the incubation time of unseeded control films. Furthermore, films with larger initial seed densities exhibited earlier crystallization onset. A separate study also was performed in which the dark conductivity was compared between films re-crystallized from various initial seed densities.

scholarly journals Capacitance Analysis of the Structures with the a-Si:H(i)/c-Si(p) Heterojunction for Solar-Cell Applications

2014 ◽  
Vol 65 (4) ◽  
pp. 254-258 ◽  
Author(s):  
Miroslav Mikolášek ◽  
Ján Jakaboviš ◽  
Vlastimil Řeháček ◽  
Ladislav Harmatha ◽  
Robert Andok
Keyword(s):  
Solar Cell ◽  
Amorphous Silicon ◽  
Crystalline Silicon ◽  
Amorphous Layer ◽  
Band Offset ◽  
Defect States ◽  
Conduction Band Offset ◽  
Silicon Heterojunction Solar Cell ◽  
Density Of Defect States ◽  
Passivated Silicon

Abstract In this paper we present the capacitance study of the intrinsic amorphous silicon/crystalline silicon heterostructure with the aim to gain insight on the heterointerface properties of a passivated silicon heterojunction solar cell. It is shown that due to the high density of defect states in the amorphous layer the structure has to be analyzed as a heterojunction. Using the analysis, the following values have been determined: conduction-band offset of 0.13 eV, electron affinity of 3.92 eV, and density of defect states in the intrinsic amorphous silicon being that of 4.14 X 1021m—3.

scholarly journals Material and solar cell research in high efficiency micromorph tandem solar cell

2015 ◽  
Vol 37 ◽  
pp. 434 ◽  
Author(s):  
Razagh Hafezi ◽  
Soroush Karimi ◽  
Sharie Jamalzae ◽  
Masoud Jabbari
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Solar Cell ◽  
Amorphous Silicon ◽  
High Efficiency ◽  
Crystalline Silicon ◽  
Chemical Vapour ◽  
Microcrystalline Silicon ◽  
Tandem Solar Cells ◽  
Bottom Cell

“Micromorph” tandem solar cells consisting of a microcrystalline silicon bottom cell and an amorphous silicon top cell are considered as one of the most promising new thin-film silicon solar-cell concepts. Their promise lies in the hope of simultaneously achieving high conversion efficiencies at relatively low manufacturing costs. The concept was introduced by IMT Neuchâtel, based on the VHF-GD (very high frequency glow discharge) deposition method. The key element of the micromorph cell is the hydrogenated microcrystalline silicon bottom cell that opens new perspectives for low-temperature thin-film crystalline silicon technology. This paper describes the use, within p–i–n- and n–i–p-type solar cells, of hydrogenated amorphous silicon (a-Si:H) and hydrogenated microcrystalline silicon (_c-Si:H) thin films (layers), both deposited at low temperatures (200_C) by plasma-assisted chemical vapour deposition (PECVD), from a mixture of silane and hydrogen. Optical and electrical properties of the i-layers are described. Finally, present performances and future perspectives for a high efficiency ‘micromorph’ (mc-Si:Hya-Si:H) tandem solar cells are discussed.

scholarly journals Fabrication of a Hydrogenated Amorphous Silicon detector in 3-D Geometry and Preliminary Test on Planar Prototypes

2021 ◽  
Author(s):  
Mauro Menichelli ◽  
Marco Bizzarri ◽  
Maurizio Boscardin ◽  
Mirco Caprai ◽  
Anna Paola Caricato ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Leakage Current ◽  
Collection Efficiency ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapour ◽  
Silicon Detector ◽  
Preliminary Test ◽  
X Rays ◽  
Charge Collection Efficiency ◽  
Hydrogenated Amorphous

Hydrogenated amorphous silicon (a-Si:H) can be produced by plasma-enhanced chemical vapour deposition (PECVD) of SiH4 (Silane) mixed with Hydrogen. The resulting material shows outstanding radiation resistance properties and can be deposited on a wide variety of different substrates. These devices have been used to detect many different kinds of radiation namely: MIPs, x-rays, neutrons and ions as well as low energy protons and alphas. However, MIP detection using planar diodes has always been difficult due to the unsatisfactory S/N ratio arising from a combination of high leakage current, high capacitance and a limited charge collection efficiency (50% at best for a 30 µm planar diode). To overcome these limitations the 3D-SiAm collaboration proposes to use a 3D detector geometry. The use of vertical electrodes allows for a small collection distance to be maintained while conserving a large detector thickness for charge generation. The depletion voltage in this configuration can be kept below 400 V with consequent reduction in the leakage current. In this paper, following a detailed description of the fabrication process, the results of the tests performed on the planar p-i-n structures made with ion implantation of the dopants and with carrier selective contacts will be illustrated.

In situ crystallization of amorphous silicon

1992 ◽  
Vol 50 (2) ◽  
pp. 1346-1347
Author(s):  
J.L. Batstone
Keyword(s):  
Phase Transformation ◽  
Amorphous Silicon ◽  
Crystalline Silicon ◽  
Amorphous Film ◽  
State Transformation ◽  
Solid State Transformation ◽  
Plan View ◽  
The Difference ◽  
Si Films

The solid state transformation of amorphous silicon (a-Si) to crystalline silicon (c-Si) is a first order phase transformation which is driven by the difference in free energy between the amorphous and crystalline phases. The crystallization occurs at temperatures of 500-700°C which are readily accessible with commercial specimen heating stages for the transmission electron microscope (TEM). In this paper we study the a-c phase transformation dynamically by utilizing the powerful technique of in-situ TEM to monitor the nucleation and growth kinetics of thin films of Si. The propagation of a moving a-c interface is presented and an activation energy for crystal growth is obtained.400Å of a-Si was prepared by electron beam deposition of Si at room temperature on amorphous Si3,N4 “window” substrates which required no additional sample preparation for TEM. The samples were examined in a plan view orientation to minimize surface effects on the crystallization process. The a-Si films were annealed by in-situ heating in a Gatan single-tilt hot stage which has a temperature accuracy of ±25°C. Crystallization occurred at ∼700°C with the formation of small crystallites which grew to consume the entire amorphous film. Fig. 1 shows a partially transformed region of a-Si after annealing at 710°C for 6 mins.

Oxidation Reduction in Nanocrystalline Silicon Grown by Hydrogen-Profiling Technique

2016 ◽  
Vol 41 ◽  
pp. 9-17 ◽  
Author(s):  
Christopher J. Arendse ◽  
Theophillus F.G. Muller ◽  
Franscious R. Cummings ◽  
Clive J. Oliphant
Keyword(s):  
Amorphous Silicon ◽  
Hydrogen Concentration ◽  
Film Growth ◽  
Volume Fraction ◽  
Crystalline Silicon ◽  
Chemical Vapour ◽  
Silicon Layer ◽  
Nanocrystalline Silicon ◽  
Substrate Interface ◽  
Nano Crystalline

The deposition of a compact amorphous silicon/nano-crystalline silicon material is demonstrated by hot-wire chemical vapour deposition using a sequential hydrogen profiling technique at low hydrogen dilutions. Nano-crystallite nucleation occurs at the substrate interface that develops into a uniform, porous crystalline structure as the growth progresses. A further reduction in the H-dilution results in the onset of a dense amorphous silicon layer. The average crystalline volume fraction and nano-crystallite size in the sample bulk amounts to 30% and 6 nm, respectively, as probed by Raman spectroscopy using the 647 nm excitation. The change in hydrogen dilution is accompanied by a graded hydrogen concentration depth-profile, where the hydrogen concentration decreases as the growth progresses. The level of post-deposition oxidation is considerably reduced, as inferred from infrared spectroscopy. The presence of oxygen is mainly confined to the substrate interface as a result of thermal oxidation during thin film growth.

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