Microscaled and nanoscaled platinum sensors

We show small and robust platinum resistive heaters and thermometers that are defined by microlithography on silicon substrates. These devices can be used for a wide range of applications, including thermal sensor arrays, programmable thermal sources, and even incandescent light emitters. To explore the miniaturization of such devices, we have developed microscaled and nanoscaled platinum resistor arrays with wire widths as small as 75 nm, fabricated lithographically to provide highly localized heating and accurate resistance (and hence temperature) measurements. We present some of these potential applications of microfabricated platinum resistors in sensing and spectroscopy

Enhancement of antimonide-based p-channel quantum-well field effect transistors using process-induced sprain

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (p. 55-57).For decades, the scaling of silicon CMOS has brought impressive growth to the semiconductor industry, as well as a wealth of technological innovations. However, the continued scaling of CMOS devices to the nanometer regime is now threatened by intrinsic limitations to the use of silicon as the channel material. Hence, there is a strong interest in III-V semiconductor materials to replace silicon as the channel material as a result of their outstanding electron transport properties. While III-V materials have demonstrated impressive n-channel field-effect transistors (FETs), the same success has not yet been translated to the development of a high-performance III-V pchannel FET. This is because while many III-V's have high electron mobilities, they generally have very poor hole mobilities. The development of a high-performance III-V p-channel FET is critical to the realization of a future-generation III-V CMOS architecture. Among the III-Vs, the antimonides have the highest hole mobilities. This makes them attractive for developing a 111-V p-channel FET. This thesis examines the use of process-induced uniaxial strain combined with biaxial strain introduced during growth of the heterostructure as an approach to enhance antimonide-based FETs. Using a compressively stressed silicon nitride layer to induce uniaxial strain in the device, stressed devices with an InGaSb channel were fabricated and compared with unstressed devices processed in parallel. Enhancements of >50% in the intrinsic transconductance were observed as well as reductions of >30% in the source-drain resistance. This work illustrates the effectiveness of uniaxial strain in improving the performance of antimonide FETs.by Luke Guo.S.M

Thermal Blood Clot Formation and use in Microfluidic Device Valving Applications

The present invention provides a method of forming a blood-clot microvalve by heating blood in a capillary tube of a microfluidic device. Also described are methods of modulating liquid flow in a capillary tube by forming and removing a blood-clot microvalve

Instructional Design With a Language Lens: Preparing Educators for Multilingual Classrooms

Classrooms are more diverse than ever before with increasing numbers of multilingual students who are developing English proficiency while simultaneously being expected to learn and perform in English in literacy and the content areas. In the context of the United States, previous efforts to prepare teachers for the heterogeneous population of students have led to simplified curriculum that limits children’s equitable access to rigorous disciplinary learning. This chapter probes one project’s efforts to build capacity in schools by holistically preparing educators across grades and disciplines to provide equitable instruction for students labeled as English learners. Using a framework that added a language lens to the understanding by design framework already used in partner schools, participants developed understandings and practices that facilitated curricular design that maintained focus on language across instruction

Hybridization gap versus hidden order gap in URu2_2Si2_2 as revealed by optical spectroscopy

We present the in-plane optical reflectance measurement on single crystals of URu$_2$As$_2$. The study revealed a strong temperature-dependent spectral evolution. Above 50 K, the low frequency optical conductivity is rather flat without a clear Drude-like response, indicating a very short transport life time of the free carriers. Well below the coherence temperature, there appears an abrupt spectral weight suppression below 400 cm$^{-1}$, yielding evidence for the formation of a hybridization energy gap arising from the mixing of the conduction electron and narrow f-electron bands. A small part of the suppressed spectral weight was transferred to the low frequency side, leading to a narrow Drude component, while the majority of the suppressed spectral weight was transferred to the high frequency side centered near 4000 cm$^{-1}$. Below the hidden order temperature, another very prominent energy gap structure was observed, which leads to the removal of a large part of the Drude component and a sharp reduction of the carrier scattering rate. The study revealed that the hybridization gap and the hidden orger gap are distinctly different: they occur at different energy scales and exhibit completely different spectral characteristics.Comment: 5 page