The DC and RF characteristics of double heterojunction bipolar transistors (DHBTs) with a compressively strained InGaAsSb base prepared by solid-source molecular beam epatixy (MBE) are investigated. Compared with conventional InGaAs/InP DHBT structures, the proposed InGaAsSb/InP HBT exhibits lower baseemitter turn-on voltage and VCE-offset voltage. Also observed are the high collector current d...

To understand inhomogeneous reactions perpendicular to the current collector in an electrode for batteries, a method combining operando synchrotron X-ray diffraction and two-layer electrodes with different porosities is developed. The two layers are built using two different active materials (LiNi0.80Co0.15Al0.05O2 and LiMn2O4), therefore, tracing each diffraction pattern reveals which active m...

Equation 1 is the general idealized exponential expression for the emitter current Ie of a BJT in forward active operation. The logarithmic relationship is applicable over several orders of magnitude of collector current. Apply this expression to each transistor in the differential configuration (assume ß >> 1 so that emitter current ≈ collector current); the difference of the expressions for t...

Many challenges must be overcome in order to create reliable electrochemical energy storage devices with not only high energy but also high power densities. Gaps exist in both battery and supercapacitor technologies, with neither one satisfying the need for both large power and energy densities in a single device. To begin addressing these challenges (and others), we report a process to create ...

Fibre optic sensors are excellent tools to use for monitoring high-voltage current collectors. Because of their small cross section and electrical neutrality, they are easily integrated into the current collector strip and are well specialized for detection of high-speed load events. The conventional contact force measurement with four force sensors below the collector strips can also be simpli...

Flexible energy storage devices are highly demanded for various applications. Carbon cloth (CC) woven by carbon fibers (CFs) is typically used as electrode or current collector for flexible devices. The low surface area of CC and the presence of big gaps (ca. micro-size) between individual CFs lead to poor performance. Herein, we interconnect individual CFs through the in-situ exfoliated graphe...

Ge nanowire electrodes fabricated by using vapor-liquid-solid growth on metallic current collector substrates were found to have good performance during cycling with Li. An initial discharge capacity of 1141 mA.h/g was found to be stable over 20 cycles at the C/20 rate. High power rates were also observed up to 2C with Coulombic efficiency > 99%. Structural characterization revealed that the Ge...