There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Interfacial thermal resistance is the primary impediment to heat flow in materials and devices as characteristic lengths become comparable to the mean-free paths of the energy carriers. This thermal boundary conductance across solid interfaces at the nanoscale can affect a plethora of applications. The recent experimental and computational advances that have led to significant atomistic insights into the nanoscopic thermal transport mechanisms at interfaces between various types of materials are summarized. The authors focus on discussions of works that have pushed the limits to interfacial heat transfer and drastically increased the understanding of thermal boundary conductance on the atomic and nano meter scales near solid/solid interfaces. Specifically, the role of localized interfacial modes on the energy conversion processes occurring at interfaces is emphasized in this review. The authors also focus on experiments and computational works that have challenged the traditionally used phonon gas models in interpreting the physical mechanisms driving interfacial energy transport. Finally, the authors discuss the future directions and avenues of research that can further the knowledge of heat transfer across systems with broken symmetries.

A Review of Experimental and Computational Advances in Thermal Boundary Conductance and Nanoscale Thermal Transport across Solid Interfaces

Naked to the Bone: Medical Imaging in the Twentieth Century

Lacking rich and realistic data, learned single image denoising algorithms generalize poorly in real raw images that not resemble the data used for training. Although the problem can be alleviated by the heteroscedastic Gaussian noise model, the noise sources caused by digital camera electronics are still largely overlooked, despite their significant effect on raw measurement, especially under extremely low-light condition. To address this issue, we present a highly accurate noise formation model based on the characteristics of CMOS photosensors, thereby enabling us to synthesize realistic samples that better match the physics of image formation process. Given the proposed noise model, we additionally propose a method to calibrate the noise parameters for available modern digital cameras, which is simple and reproducible for any new device. We systematically study the generalizability of a neural network trained with existing schemes, by introducing a new low-light denoising dataset that covers many modern digital cameras from diverse brands. Extensive empirical results collectively show that by utilizing our proposed noise formation model, a network can reach the capability as if it had been trained with rich real data, which demonstrates the effectiveness of our noise formation model.

/pdf/a-physics-based-noise-formation-model-for-extreme-low-light-3grd8oop5f.pdf

A Physics-Based Noise Formation Model for Extreme Low-Light Raw Denoising

The free charge-transfer characteristics of charge-coupled devices (CCD's) are analyzed in terms of the charge motion due to thermal diffusion, self-induced drift, and fringing field drift. The charge-coupled structures considered have separations between the gates equal to the thickness of the channel oxide. The effect of each of the above mechanisms on charge transfer is first considered separately, and a new method is presented for the calculation of the self-induced field. Then the results of a computer simulation of the charge-transfer process that simultaneously considers all three charge-motion mechanisms is presented for three-phase CCD's with gate lengths of 4 and 10 µ. The analysis shows that while the majority of the charge is transferred by means of the self-induced drift that follows a hyperbolic time dependence, the last few percent of the charge decays exponentially under the influence of the fringing field drift or thermal diffusion, depending on the design of the structure. The analysis shows that in CCD's made on relatively high resistivity substrates, the transfer by fringing-field drift can be very fast, such that transfer efficiencies of 99.99 percent are expected at 5- to 10- MHz bit rates for 10-µ gate lengths and at up to 100 MHz for 4-µ gate lengths.

Free charge transfer in charge-coupled devices

The pinned photodiode is the primary photodetector structure used in most CCD and CMOS image sensors. This paper reviews the development, physics, and technology of the pinned photodiode.

/pdf/a-review-of-the-pinned-photodiode-for-ccd-and-cmos-image-k6m9rzdt3n.pdf

A Review of the Pinned Photodiode for CCD and CMOS Image Sensors

As demand for lower power and higher performance nano-electronic products increases, the semiconductor industry must adopt insulating materials with progressively lower dielectric constants (ie low-k) in order to minimize capacitive related power losses in integrated circuits However in addition to a lower dielectric constant, low-k materials typically exhibit many other reduced material properties that have limited the ability of the semiconductor industry to implement them In this article, we demonstrate that the reduced material properties exhibited by low-k materials can be understood based on bond constraint and percolation theory Using a-SiC:H as a case study material, we utilize nuclear reaction analysis, Rutherford backscattering, nuclear magnetic resonance and transmission Fourier transform infra-red spectroscopy measurements to determine the average coordination (〈r〉) for these materials Correlations of 〈r〉 to Young's modulus, hardness, thermal conductivity, resistivity, refractive index, intrinsic stress, mass density and porosity show that an extremely wide range in material properties (in some cases several orders of magnitude) can be achieved through reducing 〈r〉 via the controlled incorporation of terminal Si Hx and C Hx groups We also demonstrate that the critical point at 〈r〉 ≤ 24 predicted by constraint theory exists in this material system and places limitations on the range of properties that can be achieved for future low-k a-SiC:H materials

https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=914260

Influence of network bond percolation on the thermal, mechanical, electrical and optical properties of high and low-k a-SiC:H thin films

Thermal conductivity and sound velocity measurements of plasma enhanced chemical vapor deposited a-SiC:H thin films

The Quanta Image Sensor (QIS) concept and recent work on its associated jot device are discussed. A bipolar jot and a pump-gate jot are described. Both have been modelled in TCAD. As simulated, the pump-gate jot has a full well of 200e- and conversion gain of 480uV/e-.

/pdf/jot-devices-and-the-quanta-image-sensor-2ro23gjtta.pdf

Jot devices and the Quanta Image Sensor

We have measured the attenuation of longitudinal acoustic waves in a series of amorphous and nanocrystalline silicon films using picosecond ultrasonics The films were grown using a modified very high frequency glow discharge method on steel substrates The deposition conditions were similar to that used in the fabrication of high-efficiency solar cells The film thicknesses were varied so we could distinguish between interface losses and intrinsic losses within the silicon films We determine the attenuation of amorphous Si to be 780 \ifmmode\pm\else\textpm\fi{} 160 cm${}^{\ensuremath{-}1}$ at 100 GHz and 340 \ifmmode\pm\else\textpm\fi{} 120 cm${}^{\ensuremath{-}1}$ at 50 GHz, values that are lower than those predicted by theories based on anharmonic interactions of the sound wave with localized phonons or extended resonant modes We determine the attenuation of nanocrystalline Si at 50 GHz to be nearly an order of magnitude higher than amorphous Si (2600 \ifmmode\pm\else\textpm\fi{} 660 cm${}^{\ensuremath{-}1}$) and compare that value to a simple Rayleigh scattering prediction

/pdf/ultrasonic-attenuation-in-amorphous-silicon-at-50-and-100-4dvr11cnwl.pdf

Donald Hondongwa

Papers

A Review of the Pinned Photodiode for CCD and CMOS Image Sensors

Influence of network bond percolation on the thermal, mechanical, electrical and optical properties of high and low-k a-SiC:H thin films

Thermal conductivity and sound velocity measurements of plasma enhanced chemical vapor deposited a-SiC:H thin films

Jot devices and the Quanta Image Sensor

Ultrasonic attenuation in amorphous silicon at 50 and 100 GHz