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Articles 1 - 11 of 11
Full-Text Articles in Engineering
Mems Resonant Magnetic Field Sensor Based On An Aln/Fegab Bilayer Nano-Plate Resonator, Yu Hui, Tianxiang Nan, Nian Sun, Matteo Rinaldi
Mems Resonant Magnetic Field Sensor Based On An Aln/Fegab Bilayer Nano-Plate Resonator, Yu Hui, Tianxiang Nan, Nian Sun, Matteo Rinaldi
Tianxiang Nan
This paper reports on the first demonstration of an ultra-miniaturized, high frequency (215 MHz) and high sensitivity MEMS resonant magnetic field sensor based on an AlN/FeGaB bilayer nano-plate resonator capable of detecting magnetic field at nano-Tesla level. Despite of the reduced volume and the high operating frequency of the sensor, high electromechanical performances were achieved (quality factor Q ≈ 511 and electromechanical coupling coefficient kt² ≈ 1.63%). This first prototype was characterized for different magnetic field levels from 0 to 152 Oe showing a frequency sensitivity of ~ 1 Hz/nT and a limit of detection of ~ 10 nT.
A Shade Tolerant Panel Design For Thin Film Photovoltaics, Sourabh Dongaonkar, Muhammad Alam
A Shade Tolerant Panel Design For Thin Film Photovoltaics, Sourabh Dongaonkar, Muhammad Alam
Sourabh Dongaonkar
We analyze the problem of partial shading of thin film photovoltaic (TFPV) panels, using full two dimensional circuit simulations. By accounting for the panel structure and typical array configurations, we can accurately account for the effect of various shading configurations at the cell and panel level. We demonstrate the limitation of external bypass diodes in protecting shaded cells from reverse breakdown, and explore the whole range of shading scenarios and their impact on reverse stress experienced by shaded cells. Based on the analysis, we identify the key aspects of shading problem, and formulate design rules for shadow aware geometrical design …
End-To-End Modeling For Variability And Reliability Analysis Of Thin Film Pv, Sourabh Dongaonkar, Muhammad Alam
End-To-End Modeling For Variability And Reliability Analysis Of Thin Film Pv, Sourabh Dongaonkar, Muhammad Alam
Sourabh Dongaonkar
We present an end-to-end modeling framework, spanning the device, module and also system levels, for analyzing thin film photovoltaics (PV). This approach is based on embedding a detailed, statistically relevant, physics based equivalent circuit into module and array level simulations. This approach enables us to analyze key variability and reliability issues in thin film PV, and allows us to interpret their effect on process yield and intrinsic module lifetimes. Our results suggest that the time-zero gap between cell and module efficiencies, a key variability concern for thin-film PV, can be attributed to processrelated shunts with log-normal PDF distributed randomly across …
Reverse Stress Metastability Of Shunt Current In Cigs Solar Cells, Sourabh Dongaonkar, Erik Sheets, Rakesh Agrawal, Muhammad Alam
Reverse Stress Metastability Of Shunt Current In Cigs Solar Cells, Sourabh Dongaonkar, Erik Sheets, Rakesh Agrawal, Muhammad Alam
Sourabh Dongaonkar
Partial shading in thin film solar panels can result in reverse bias stress across shaded cells. Therefore, it is important to understand the effect of such reverse stress in commercially competitive PV technologies such as CIGS. In this paper, we systematically investigate the effect of moderate reverse bias on solution-processed CIGS solar cells. We subject the solar cells to varying degrees of reverse biases and continuously monitor the impact of the stress on dark current. We also explore the relaxation behavior of dark current following passive storage and the long term effect of the shadow stress on power output of …
A Physical Model For Non-Ohmic Shunt Conduction And Metastability In Amorphous Silicon P-I-N Solar Cells, Sourabh Dongaonkar, Karthik Y, Souvik Mahapatra, Muhammad Alam
A Physical Model For Non-Ohmic Shunt Conduction And Metastability In Amorphous Silicon P-I-N Solar Cells, Sourabh Dongaonkar, Karthik Y, Souvik Mahapatra, Muhammad Alam
Sourabh Dongaonkar
We present a physical model of non-ohmic shunt current in a-Si:H p-i-n solar cells, and validate it with detailed measurements. This model is based on space-charge-limited (SCL) transport through localized p-i-p shunt paths, which can arise from contact metal incorporation in a-Si:H layer. This model explains both the electrical characteristics and the metastable switching behavior of the shunts within an integrated framework. We first verify the SCL model using simulations and statistically robust measurements, and then use this picture to analyze our systematic observations of non-volatile switching in these shunts. Our work not only resolves broad experimental observations on shunt …
On The Nature Of Shunt Leakage In Amorphous Silicon P-I-N Solar Cells, Sourabh Dongaonkar, Karthik Y, Dapeng Wang, Michel Frei, Souvik Mahapatra, Muhammad Alam
On The Nature Of Shunt Leakage In Amorphous Silicon P-I-N Solar Cells, Sourabh Dongaonkar, Karthik Y, Dapeng Wang, Michel Frei, Souvik Mahapatra, Muhammad Alam
Sourabh Dongaonkar
In this letter, we investigate the nature of shunt leakage currents in large-area (on the order of square centimeters) thin-film a-Si:H p-i-n solar cells and show that it is characterized by following universal features: 1) voltage symmetry; 2) power-law voltage dependence; and 3) weak temperature dependence. The voltage symmetry offers a robust empirical method to isolate the diode current from measured “shunt-contaminated” forward dark IV . We find that space-charge-limited current provides the best qualitative explanation for the observed features of the shunt current. Finally, we discuss the possible physical origin of localized shunt paths in the light of experimental …
Identification, Characterization, And Implications Of Shadow Degradation In Thin Film Solar Cells, Sourabh Dongaonkar, Karthik Y, Dapeng Wang, Michel Frei, Souvik Mahapatra, Muhammad Alam
Identification, Characterization, And Implications Of Shadow Degradation In Thin Film Solar Cells, Sourabh Dongaonkar, Karthik Y, Dapeng Wang, Michel Frei, Souvik Mahapatra, Muhammad Alam
Sourabh Dongaonkar
We describe a comprehensive study of intrinsicreliability issue arising from partial shadowing of photovoltaicpanels (e.g., a leaf fallen on it, a nearby tree casting a shadow,etc.). This can cause the shaded cells to be reverse biased, causingdark current degradation. In this paper, (1) we calculate thestatistical distribution of reverse bias stress arising from variousshading configurations, (2) identify the components of darkcurrent, and provide a scheme to isolate them, (3) characterizethe effect of reverse stress on the dark current of a-Si:H p-i-ncells, and (4) finally, combine these features of degradationprocess with shadowing statistics, to project ‘shadow-degradation’ (SD) over the operating lifetime …
Physics And Statistics Of Non-Ohmic Shunt Conduction And Metastability In Amorphous Silicon P-I-N Solar Cells, Sourabh Dongaonkar, Karthik Yogendra, Souvik Mahapatra, Muhammad Alam
Physics And Statistics Of Non-Ohmic Shunt Conduction And Metastability In Amorphous Silicon P-I-N Solar Cells, Sourabh Dongaonkar, Karthik Yogendra, Souvik Mahapatra, Muhammad Alam
Sourabh Dongaonkar
In this paper, we present a physical model of the non- Ohmic shunt current ISH in amorphous silicon (a-Si:H) p–i–n solar cells and validate it with detailed measurements. This model is based on space-charge-limited (SCL) transport through localized p–i–p shunt paths. These paths can arise from n-contact metal incorporation in the a-Si:H layer, causing the (n)a-Si:H to be counterdoped to p-type. The model not only explains all the electrical characteristics of preexisting shunts but also provides insight into the metastable switching that is observed in the shunt-dominated region of dark current as well.We first verify the SCL model using simulations …
Mems Resonant Magnetic Field Sensor Based On An Aln/Fegab Bilayer Nano-Plate Resonator, Yu Hui, Tianxiang Nan, Nian Sun, Matteo Rinaldi
Mems Resonant Magnetic Field Sensor Based On An Aln/Fegab Bilayer Nano-Plate Resonator, Yu Hui, Tianxiang Nan, Nian Sun, Matteo Rinaldi
Matteo Rinaldi
This paper reports on the first demonstration of an ultra-miniaturized, high frequency (215 MHz) and high sensitivity MEMS resonant magnetic field sensor based on an AlN/FeGaB bilayer nano-plate resonator capable of detecting magnetic field at nano-Tesla level. Despite of the reduced volume and the high operating frequency of the sensor, high electromechanical performances were achieved (quality factor Q ≈ 511 and electromechanical coupling coefficient kt² ≈ 1.63%). This first prototype was characterized for different magnetic field levels from 0 to 152 Oe showing a frequency sensitivity of ~ 1 Hz/nT and a limit of detection of ~ 10 nT.
Cause And Prevention Of Moisture-Induced Degradation Of Resistance Random Access Memory Nanodevices, Albert Chen
Cause And Prevention Of Moisture-Induced Degradation Of Resistance Random Access Memory Nanodevices, Albert Chen
Albert B Chen
Dielectric thin films in nanodevices may absorb moisture, leading to physical changes and property/performance degradation, such as altered data storage and readout in resistance random access memory. Here we demonstrate using a nanometallic memory that such degradation proceeds via nanoporosity, which facilitates water wetting in otherwise nonwetting dielectrics. Electric degradation only occurs when the device is in the charge-storage state, which provides a nanoscale dielectrophoretic force directing H2O to internal field centers (sites of trapped charge) to enable bond rupture and charged hydroxyl formation. While these processes are dramatically enhanced by an external DC or AC field and electron-donating electrodes, …
Demonstration And Modeling Of Multi-Bit Resistance Random Access Memory, Albert Chen
Demonstration And Modeling Of Multi-Bit Resistance Random Access Memory, Albert Chen
Albert B Chen
Although intermediates resistance states are common in resistance random access memory (RRAM), two-way switching among them has not been demonstrated. Using a nanometallic bipolar RRAM, we have illustrated a general scheme for writing/rewriting multi-bit memory using voltage pulses. Stability conditions for accessing intermediate states have also been determined in terms of a state distribution function and the weight of serial load resistance. A multi-bit memory is shown to realize considerable space saving at a modest decrease of switching speed.