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Narrowing of band gap at source/drain contact scheme of nanoscale InAs–nMOS
A multi-scale simulation study of Ni/InAs nano-scale contact aimed for the sub-14 nm technology is carried out to understand material and transport properties at a metal-semiconductor interface. The deposited Ni metal contact on an 11 nm thick InAs channel forms an 8.5 nm thick InAs leaving a 2.5 nm thick InAs channel on a ptype doped (1x10(16) cm(-3)) AlAs 0.47 Sb 0.53 buffer. The density functional theory (DFT) calculations reveal a band gap narrowing in the InAs at the metal-semiconductor interface. The one-dimensional (1D) self-consistent Poisson-Schrodinger transport simulations using real-space material parameters extracted from the DFT calculations at the metal-semiconductor interface, exhibiting band gap narrowing, give a specific sheet resistance of R-sh= 90.9 Omega/sq which is in a good agreement with an experimental value of 97 Omega/sq.
Effective hole extraction using MoO{sub x}-Al contact in perovskite CH{sub 3}NH{sub 3}PbI{sub 3} solar cells
We report an 11.4%-efficient perovskite CH{sub 3}NH{sub 3}PbI{sub 3} solar cell using low-cost molybdenum oxide/aluminum (i.e., MoO{sub x}/Al) as an alternative top contact to replace noble/precious metals (e.g., Au or Ag) for extracting photogenerated holes. The device performance of perovskite solar cells using a MoO{sub x}/Al top contact is comparable to that of cells using the standard Ag top contact. Analysis of impedance spectroscopy measurements suggests that using 10-nm-thick MoO{sub x} and Al does not affect charge-recombination properties of perovskite solar cells. Using a thicker (20-nm) MoO{sub x} layer leads to a lower cell performance caused mainly by a reduced fill factor. Our results suggest that MoO{sub x}/Al is promising as a low-cost and effective hole-extraction contact for perovskite solar cells.
Crystals of $\mathrm{TELSAM}$–target protein fusions that exhibit minimal crystal contacts and lack direct inter-$\mathrm{TELSAM}$ contacts
While conducting pilot studies into the usefulness of fusion to TELSAM polymers as a potential protein crystallization strategy, we observed novel properties in crystals of two TELSAM–target protein fusions, as follows. (i) A TELSAM–target protein fusion can crystallize more rapidly and with greater propensity than the same target protein alone. (ii) TELSAM–target protein fusions can be crystallized at low protein concentrations. This unprecedented observation suggests a route to crystallize proteins that can only be produced in microgram amounts. (iii) The TELSAM polymers themselves need not directly contact one another in the crystal lattice in order to form well-diffracting crystals. This novel observation is important because it suggests that TELSAM may be able to crystallize target proteins too large to allow direct inter-polymer contacts. (iv) Flexible TELSAM–target protein linkers can allow target proteins to find productive binding modes against the TELSAM polymer. (v) TELSAM polymers can adjust their helical rise to allow fused target proteins to make productive crystal contacts. (vi). Fusion to TELSAM polymers can stabilize weak inter-target protein crystal contacts. We report features of these TELSAM–target protein crystal structures and outline future work needed to validate TELSAM as a crystallization chaperone and determine best practices for its use.
Nondestructive Contact Resistivity Measurements on Solar Cells Using the Circular Transmission Line Method
Not provided.
CdSexTe1-x/CdTe Devices with Reduced Interface Recombination Through Novel Back Contacts and Group-V Doping
Since excellent carrier lifetimes and front interface electronic quality are now achieved, rear interface recombination can limit V OC in CdSexTe1-x/CdTe solar cells. Several back-contact structures for devices were fabricated using combinations of tellurium, aluminum oxide, amorphous silicon, and indium tin oxide (ITO). Time-resolved photoluminescence was used to characterize such structures. We show increasingly improved interface passivation through the subsequent use of aluminum oxide, amorphous silicon, and ITO. Additionally, we show that arsenic-doped absorbers form a more passive interface with numerous back contact structures.
Contact detection and contact motion for error recovery in the presence of uncertainties
Due to various kinds of uncertainties, a robot motion may fail and result in some unintended contact between the object held by the robot and the environment, which greatly hampers robotics applications on tasks with high-precision requirements, such as assembly tasks. Aiming at automatically recovering a robotic task from such a failure, this paper discusses, in the presence of uncertainties, contact detection based on contact motion for recovery. It presents a framework for on-line recognizing contacts using multiple sensor modalities in the presence of sensing uncertainties and means for ensuring successful compliant motions in the presence of sensing and control uncertainties.
Phosphorus replenishment to improve the contact resistivity of light-induced Al contacts on Si solar cells
A method to repair laser-induced phosphorus loss from the n-type emitter of Si solar cells during light-induced Al plating is demonstrated. The ability to add a water-reactive phosphorus compound, PCl 5 , into the Al plating bath gives a unique advantage to Al over Cu for front contacts on Si solar cells. The contact resistivity between light-induced Al and Si emitter is reduced to as low as 0.1 mΩ-cm 2 . Cyclic voltammetry performed on a plating bath composed of 81 wt% 1-ethyl-3-methylimidazolium tetrachloroaluminate, 19 wt% AlCl 3 , and 0.2 wt% PCl 5 reveals multiple reduction reactions of PCl 5 , although incomplete decomposition of PCl 5 is possible. A decrease in nucleation loop size during cyclic voltammetry is also observed suggesting that PCl 5 , while being consumed, modifies the growth mechanism during Al plating. Structural analysis confirms that the addition of PCl 5 produces an Al film which is levelized and compact. Here, a pulsed voltage profile coupled with chemical analysis verifies that phosphorus incorporation is electrolytically activated and is likely the cause for the low contact resistivity.
Acoustic Mismatch Model for Thermal Contact Conductance of Van Der Waals Contacts Under Static Force
We report that Van der Waals interfaces play a major role in technology today. Thermal transport in material systems with van der Waals interfaces is mainly limited by the contact conductance. Although the effects of static force, such as pressure or the electrostatic part of hydrogen bonds, on the thermal contact conductance of van der Waals interfaces have been examined in a few studies, the focus was either on numerical simulation using techniques such as molecular dynamics or on experimental investigation. In this article, an analytical model of thermal contact conductance that accounts for the effects of static force and adhesion energy is presented. The application of static forces is found to cause a decrease in the intermolecular distance, which leads to increased interatomic forces across the interfaces and thus higher thermal conductance. The model is in good agreement with experimental data on the effect of pressure on thermal conductance collected by Gotsmann and Lantz (Nature Materials, Vol. 12, p. 59–65, 2012).
Computing the contact areas of stationary and sliding contacts
Calculation of contact areas of stationary and sliding electric contacts - elastic and plastic contacts of electrodes
Ultraviolet random lasing from asymmetrically contacted MgZnO metal-semiconductor-metal device
Not Available
Investigation of the Interactions Between Low-Temperature Ag Paste Components and SiO2/Poly-Si(n) Contacts and the Impact on Contact Properties
Reducing poly-Si thickness to minimize parasitic absorption on a light-receiving side of a TOPCon solar cell without suffering voltage losses after metallization is a challenge in optimizing TOPCon performance. As an alternative to fire-through pastes, we investigate low-temperature Ag paste to SiO2/poly-Si passivating contacts through fabrication of electrical test structures to characterize the passivation quality and electrical transport across the metallized interface. With current paste chemistries, we find that solvent wetting of the poly-Si surface before evaporation and non-volatile binder resin adhesion to the surface after curing are major impediments which prevent Ag contact formation. However, low- resistance poly-Si/Ag interfaces formed with physical vapour deposition similarly degrade after annealing, indicating contacting issues related to the Ag content even in the absence of the organic paste components.
Self-Aligned Selective Area Front Contacts on Poly -Si/SiO x Passivating Contact c -Si Solar Cells
We report both polarity poly-Si/SiO x passivating contacts in a front/back device configuration may represent the next solar cell architecture after tunnel oxide passivating contacts (TOPCon) cells, but high parasitic absorption in the front poly -Si layer often limits its performance. This work explores a wet etching technique to remove the front poly -Si in the nonmetallized regions using self-aligned metal grids as an etch mask. We systematically examine various dielectric layers (SiN x ,Al 2 O 3 , and stacks thereof) to study the repassivation of the etched n + surface, and find that an SiN x /Al 2 O 3 passivation stack can effectively repassivate the etched surface, which we attribute to field-effect passivation from the positive fixed charge from the SiN x layer, and excellent chemical passivation property from Al 2 O 3 in the form of atomic H. We demonstrate a front/back poly-Si/SiO x passivating contact device, with an open-circuit voltage (V oc ) of 690 mV, short-circuit current density (J sc ) of 39.8 mA/cm 2 , fill factor of 78%, and power conversion efficiency of 21.4%. Furthermore, simulations using SunSolve and Quokka 3 show good agreement with both the optical and electrical properties of the experimental device. The power loss analysis reveals improvements in the optical loss from the back Ti adhesion and front SiN x layers would lead to a 23.5% device. Lastly, a techno-economic model compares the production cost of this improved cell with the current TOPCon cells. Our results highlight that further cost reductions in single-sided doped poly -Si layers are needed to compete with mainstream passivated emitter and rear cell, and TOPCon technologies.
Large area tunnel oxide passivated rear contact n -type Si solar cells with 21.2% efficiency: Large area tunnel oxide passivated rear contact n -type Si solar cells
This paper reports on the implementation of carrier-selective tunnel oxide passivated rear contact for high-efficiency screen-printed large area n-type front junction crystalline Si solar cells. It is shown that the tunnel oxide grown in nitric acid at room temperature (25°C) and capped with n+ polysilicon layer provides excellent rear contact passivation with implied open-circuit voltage iVoc of 714mV and saturation current density J0b of 10.3 fA/cm2 for the back surface field region. The durability of this passivation scheme is also investigated for a back-end high temperature process. In combination with an ion-implanted Al2O3-passivated boron emitter and screen-printed front metal grids, this passivated rear contact enabled 21.2% efficient front junction Si solar cells on 239 cm2 commercial grade n-type Czochralski wafers.