Two-dimensional a-Si:H/a-SiC:H n-i-p sensor array with ITO/a-SiNx antireflection coating

2005 ◽  
Vol 862 ◽  
Author(s):  
Yu. Vygranenko ◽  
J. H. Chang ◽  
A. Nathan
Keyword(s):  
Reverse Bias ◽  
Spectral Response ◽  
Charge Trapping ◽  
Optical Excitation ◽  
Antireflection Coating ◽  
Two Dimensional ◽  
Device Structure ◽  
Response Characteristics ◽  
Photodiode Array

AbstractThis paper presents a two-dimensional a–Si:H/a-SiC:H n–i–p photodiode array with switching diode readout, developed specifically for fluorescence-based bio-assays. Both device structure and fabrication processing has enabled enhancement of the external quantum efficiency of the encapsulated device up to 80%, reduction of the photodiode leakage down to 10 pA/cm2 at -1V reverse bias, and increase of the rectification current ratio of the switching diodes up to 109. The critical fabrication issues associated with deposition of device-quality materials, tailoring of defects at the i–p interface, device patterning with dry etching, junction passivation, and contact formation will be discussed. Both sensing and switching diodes were characterized. While the observed dark current in the photodiodes at low reverse bias voltages is primarily due to carrier emission from deep states in the a–Si:H bulk, the leakage in the small switching diodes stems from peripheral defects along junction sidewalls. Optical losses in the photodiodes with ITO/a–SiNx:H antireflection coating were evaluated using numerical modeling, and the calculated transmission spectra correlated well with the spectral response characteristics. Measurements of the charge transfer time and output linearity demonstrated the efficiency of the single-switching diode readout configuration. The response of the array to optical excitation was also investigated. The observed long term retardation in the signal rise and decay at illumination levels less than 1010 photons/cm2-s can be associated with charge trapping in the undoped layer.

Color separation enhancement of pixn diodes by optimizing absorption regions of a-SiGe:H/a-SiC:H alloys and using a low reflective Al-doped ZnO cathode

2012 ◽  
Vol 1426 ◽  
pp. 181-186 ◽  
Author(s):  
Andreas Bablich ◽  
Krystian Watty ◽  
Christian Merfort ◽  
Markus Boehm
Keyword(s):  
Reverse Bias ◽  
Crystalline Silicon ◽  
Spectral Response ◽  
Reverse Bias Voltage ◽  
Device Structure ◽  
Band Shift ◽  
Response Characteristics ◽  
Interference Fringes ◽  
Back Reflectors ◽  
Graded Layers

ABSTRACTSecurity imaging systems working with crystalline silicon CCD or CMOS detectors are not able to distinguish colorimetrically between a large number of dangerous chemical substances, for example whitish powders [1]. In order to offer an alternative to expensive and destructive chemical methods of analysis, we developed optimized hydrogenated amorphous silicon (a-Si:H) multicolor photodiodes with different spectral response characteristics for a reliable, fast, cheap and non-destructive identification of potentially dangerous substances. Experimental optical, C-V and I-V studies were performed to explore the effect of combining linear graded a‑SiC:H-/a‑SiGe:H layers with low-reflective ZnO:Al back-contacts. Typically, a-Si:H with profiled energy gaps can be found in tandem solar cells to optimize the collection of incoming photons [2,3]. We determined the absorption coefficients of a group of a-SiC:H and a-SiGe:H graded and non-graded layers to calculate the penetration depth of photons at different energies into the device structure. Knowing the indices of absorption, refraction and extinction, it is possible to engineer diodes in such a way that accumulations of charge carriers are generated precisely at varying device depths. Common chromium back reflectors avoid a sharp falling edge of the sensitivity towards longer wavelengths and lead to interference fringes in the spectral response [4]. By combining linear graded absorption zones and ZnO:Al back contacts, we designed an optimized device with a highly precise adjustment of the spectral sensitivity reaching from 420 nm to 560 nm and reduced interference fringes at a very low reverse bias voltage of maximum -2.5 V. Similar three terminal devices allow a shift from 440 nm to 630 nm, however, at a much higher reverse bias of -11 V at 560 nm [4]. Present research efforts concentrate on the development of fast and high dynamic front illumination device structures which ensure a continuous narrow-band shift of the spectral photosensitivity and an optimum adaption to a predetermined light source-/sample measurement configuration.

scholarly journals Silicon Waveguide Integrated with Germanium Photodetector for a Photonic-Integrated FBG Interrogator

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1683
Author(s):  
Hongqiang Li ◽  
Sai Zhang ◽  
Zhen Zhang ◽  
Shasha Zuo ◽  
Shanshan Zhang ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Dark Current ◽  
Reverse Bias ◽  
Spectral Response ◽  
Incident Light ◽  
Absorption Efficiency ◽  
Silicon On Insulator ◽  
Reverse Bias Voltage ◽  
Device Structure ◽  
Simulation And Optimization

We report a vertically coupled germanium (Ge) waveguide detector integrated on silicon-on-insulator waveguides and an optimized device structure through the analysis of the optical field distribution and absorption efficiency of the device. The photodetector we designed is manufactured by IMEC, and the tests show that the device has good performance. This study theoretically and experimentally explains the structure of Ge PIN and the effect of the photodetector (PD) waveguide parameters on the performance of the device. Simulation and optimization of waveguide detectors with different structures are carried out. The device’s structure, quantum efficiency, spectral response, response current, changes with incident light strength, and dark current of PIN-type Ge waveguide detector are calculated. The test results show that approximately 90% of the light is absorbed by a Ge waveguide with 20 μm Ge length and 500 nm Ge thickness. The quantum efficiency of the PD can reach 90.63%. Under the reverse bias of 1 V, 2 V and 3 V, the detector’s average responsiveness in C-band reached 1.02 A/W, 1.09 A/W and 1.16 A/W and the response time is 200 ns. The dark current is only 3.7 nA at the reverse bias voltage of −1 V. The proposed silicon-based Ge PIN PD is beneficial to the integration of the detector array for photonic integrated arrayed waveguide grating (AWG)-based fiber Bragg grating (FBG) interrogators.

Effects of a Bias Voltage During Hydrogenation on Passivation of the Defects in Polycrystalline Silicon for Solar Cells

2009 ◽  
Vol 1153 ◽  
Author(s):  
Yoji Saito ◽  
Hayato Kohata ◽  
Hideyuki Sano
Keyword(s):  
Solar Cells ◽  
Bias Voltage ◽  
Reverse Bias ◽  
Spectral Response ◽  
Short Circuit ◽  
Hydrogen Plasma ◽  
Short Circuit Current ◽  
Ir Absorption ◽  
Reverse Bias Voltage ◽  
Response Characteristics

AbstractThe short circuit current and conversion efficiency of the poly(multi)-crystalline solar cells are increased by the passivation process using hydrogen plasma. The passivation rate apparently increases at a reverse bias voltage near 0.6V during the hydrogenation process. The effects of the bias voltage on the passivation are large at the substrate temperatures between 200C and 250C. The phenomena are likely due to the existence of positively-ionized hydrogen, H+. The H+ ions can be accelerated from the surface into the bulk by the electric field with the negative bias. The possibility of the H+ ions in the bulk silicon has been predicted in the previous reports. The increase of the incorporated hydrogen is confirmed by IR absorption measurements. The enhanced diffusion of hydrogen induced by the reverse bias is supported by the results of spectral response characteristics of the hydrogenated solar cells.

Modelling of Moisture Movement in Wood during Outdoor Storage

2001 ◽  
Vol 6 (2) ◽  
pp. 3-14 ◽  
Author(s):  
R. Baronas ◽  
F. Ivanauskas ◽  
I. Juodeikienė ◽  
A. Kajalavičius
Keyword(s):  
Experimental Data ◽  
Finite Difference ◽  
Climatic Conditions ◽  
Two Dimensional ◽  
Moisture Movement ◽  
Finite Difference Technique ◽  
Long Term Storage ◽  
Space Formulation ◽  
Term Storage

A model of moisture movement in wood is presented in this paper in a two-dimensional-in-space formulation. The finite-difference technique has been used in order to obtain the solution of the problem. The model was applied to predict the moisture content in sawn boards from pine during long term storage under outdoor climatic conditions. The satisfactory agreement between the numerical solution and experimental data was obtained.

Electron-transport-layer-free two-dimensional perovskite solar cells based on a flexible poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) cathode

2021 ◽  
Author(s):  
Zhihai Liu ◽  
Lei Wang ◽  
Chongyang Xu ◽  
Xiaoyin Xie
Keyword(s):  
Solar Cells ◽  
Electron Transport ◽  
Power Conversion ◽  
Perovskite Solar Cells ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Two Dimensional ◽  
High Power Conversion Efficiency ◽  
Long Term Stability

Recently, Ruddlesden–Popper two-dimensional (2D) perovskite solar cells (PSCs) have been intensively studied, owing to their high power conversion efficiency (PCE) and excellent long-term stability. In this work, we fabricated electron-transport-layer-free...

Performance improvement of inverted two-dimensional perovskite solar cells using a non-fullerene acceptor as the trap passivator

2021 ◽  
Author(s):  
Eun-Cheol Lee ◽  
Zhihai Liu
Keyword(s):  
Solar Cells ◽  
Power Conversion Efficiency ◽  
Performance Improvement ◽  
High Power ◽  
Power Conversion ◽  
Perovskite Solar Cells ◽  
Two Dimensional ◽  
High Power Conversion Efficiency ◽  
Long Term Stability

Recently, Ruddlesden–Popper two-dimensional (2D) perovskite solar cells (PSCs) have been intensively studied, owing to their high power conversion efficiency (PCE) and excellent long-term stability. In this work, we improved the...

scholarly journals Perturbation of eigenvalues due to gaps in two-dimensional boundaries

2006 ◽  
Vol 463 (2079) ◽  
pp. 759-786 ◽  
Author(s):  
Anthony M.J Davis ◽  
Stefan G Llewellyn Smith
Keyword(s):  
Eigenvalue Problems ◽  
Numerical Solutions ◽  
Neumann Boundary ◽  
Diffusion Problem ◽  
Length Scale ◽  
Two Dimensional ◽  
Constructive Approach ◽  
Term Outcome ◽  
Long Term Outcome

Motivated by problems involving diffusion through small gaps, we revisit two-dimensional eigenvalue problems with localized perturbations to Neumann boundary conditions. We recover the known result that the gravest eigenvalue is O (|ln  ϵ | −1 ), where ϵ is the ratio of the size of the hole to the length-scale of the domain, and provide a simple and constructive approach for summing the inverse logarithm terms and obtaining further corrections. Comparisons with numerical solutions obtained for special geometries, both for the Dirichlet ‘patch problem’ where the perturbation to the boundary consists of a different boundary condition and for the gap problem, confirm that this approach is a simple way of obtaining an accurate value for the gravest eigenvalue and hence the long-term outcome of the underlying diffusion problem.

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