The development of high-performance tunnel junctions is critical for achieving high efficiency in multi-junction solar cells (MJSC) that can operate at high concentrations. We investigate silicon and tellurium co-doping of InGaAs quantum well inserts in p++-GaAs/n++-GaAs tunnel junctions and report a peak current density as high as 5839 A cm−2 with a series resistance of 5.86 × 10−5 Ω cm2. In addition, we discuss how device performance is affected by the growth temperature, thickness, and V/III ratio in the InGaAs layer. A simulation model indicates that the contribution of trap-assisted tunneling enhances carrier tunneling.
Mechanical alloying is used to prepare the Co[Formula: see text]Cu[Formula: see text]Si alloy. Mesoporous silicon SBA-15 is employed as the template to synthesize mesoporous carbon CMK-3. For the purpose of improving the electrochemical properties of Co[Formula: see text]Cu[Formula: see text]Si alloy, Co[Formula: see text]Cu[Formula: see text] CMK-3 ([Formula: see text], 6%, 9% and 12% mass fraction) alloys are fabricated via ball-milling. As the negative electrodes of Ni–MH batteries, the discharge capacities of alloys are tested by the LAND CT2001A tester and three-electrode system. Finally, the composite alloys show different properties for hydrogen storage. A maximum discharge capacity (558.7[Formula: see text]mAh/g) is achieved for Co[Formula: see text]Cu[Formula: see text] CMK-3 electrode. Superfluous CMK-3 is not beneficial to enhance the discharge capacity of Co[Formula: see text]Cu[Formula: see text]Si alloy. Moreover, Co[Formula: see text]Cu[Formula: see text] CMK-3 electrodes exhibit better corrosion and oxidation resistance, which leads to higher capacity retention for CMK-3/Co[Formula: see text]Cu[Formula: see text]Si composites. The comparative studies on HRD and kinetic properties of Co[Formula: see text]Cu[Formula: see text]Si and Co[Formula: see text]Cu[Formula: see text] CMK-3 are also conducted. The [Formula: see text] of Co[Formula: see text]Cu[Formula: see text]Si alloy reduces and [Formula: see text] increases after doping of CMK-3. The special structural characteristics and higher conductivity of CMK-3 can offer more electrochemical active sites and accelerate hydrogen diffusion. Accordingly, the electrochemical activity and kinetic properties are enhanced for CMK-3/Co[Formula: see text]Cu[Formula: see text]Si composites.
Air damping significantly influences the dynamical characteristics of MEMS accelerometers. Its effects at micro-scale level sharply depend on the structure layouts and size of MEMS devices. The damping phenomenon of comb microaccelerometers is investigated. The air between fixed plate electrodes and movable plate electrodes cannot flow freely and is compressed. The air damping, therefore, exhibits both viscous effects and stiffness effects. The former generates a drag force like that in macromechanical systems, and the damping force is proportional to the velocity of movable electrodes. The latter stiffens the rigidity of structure, and the stiffening level is related to the gap value of capacitors, internal pressure, and temperature. This paper focuses on the dependence of the squeeze film air damping on capacitor gaps. The simulation and experiments indicate that the squeeze film effect is sharply affected by the gap value when the structural dimensions decrease. And the influence of fabrication errors is considered in damping design in comb microaccelerometers.
The change of oxygen content of IF steel in the lining of magnesia-calcium coating was investigated from start to the end of melting.The reacted layer of coating and liquid steel was studied by SEM and EDS.It is found that three areas are formed after the steel contacts with the refractory for a certain time.With the extension of smelting time the total oxygen content of IF steel increases gradually and reaches maximum after 120 minutes,then the total oxygen content begins to decline.
Abstract The universal flexoelectric effect in solids provides a mechanical pathway for controlling electric polarization in ultrathin ferroelectrics, eliminating potential material breakdown from a giant electric field at the nanoscale. One challenge of this approach is arbitrary implementation, which is strongly hindered by one-way switching capability. Here, utilizing the innate flexibility of van der Waals materials, we demonstrate that ferroelectric polarization and domain structures can be mechanically, reversibly, and arbitrarily switched in two-dimensional CuInP 2 S 6 via the nano-tip imprinting technique. The bidirectional flexoelectric control is attributed to the extended tip-induced deformation in two-dimensional systems with innate flexibility at the atomic scale. By employing an elastic substrate, artificial ferroelectric nanodomains with lateral sizes as small as ~80 nm are noninvasively generated in an area of 1 μm 2 , equal to a density of 31.4 Gbit/in 2 . Our results highlight the potential applications of van der Waals ferroelectrics in data storage and flexoelectronics.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
