Tech Briefs

Development of High Quality 4H-SiC Thick Epitaxy for Reliable High Power Electronics Using Halogenated Precursors

New approaches to synthesizing SiC epitaxial layers could improve electronics performance.Development of robust semiconductor devices with high energy efficiency and reliability is a key objective towards 'Energy Conversion and Power Management ' for naval system applications. The goal of this research is to create the fundamental knowledge needed for the development of novel approaches to synthesize high-quality, thick SiC epitaxial layers (> 100μm) for reliable high voltage (≥10kV) / high power (>100 kW) electronics for navy ship applications.

Posted in: Briefs, TSP, Aerospace, Defense, Electronics & Computers


Silicon Based Mid-Infrared SiGeSn Heterostructure Emitters and Detectors

(a) A cross-sectional schematic of the GeSn p-i-n photodiode. (b) Dark I-V characteristics of the three samples. (c) Spectral response of the samples measured at zero bias. (d) Calculated responsivity of the samples. Enhancing the performance of GeSn p-i-n photodiodes using gold metal nanostructures.The goal of this research project was to advance the science and technology of silicon-based photonic devices using SiGeSn heterostructures. Such devices work in mid-IR spectral range and form the foundation for mid-IR photonics that enable on-chip systems for applications ranging from vibrational spectroscopy, chem/bio sensing, medical/health uses, to environmental monitoring. This project was mostly directed toward improving GeSn detectors with the use of surface plasmons induced by carefully designed metal nanostructures. The goal was to replace the current mid-IR detectors that are usually photodiodes made from narrow bandgap III-V or II-VI semiconductor compounds such as InGaAs, InSb, HgCdTe (MCT) or type-II In-GaAs/InGaSb superlattice. These photodiodes are incompatible with the CMOS process and cannot be easily integrated with Si electronics. The GeSn mid-IR detectors developed in this project are fully compatible with the CMOS process.

Posted in: Briefs, TSP, Electronics & Computers, Semiconductors & ICs, Integrated circuits, Sensors and actuators, Silicon alloys


Reconfigurable Electronics and Non-Volatile Memory Research

Investigating ways to make non-volatile memory devices smaller, lower power, more reliable, and radiation tolerant.The purpose of this research was to investigate non-volatile memory device technologies that could be applied to reconfigurable electronics applications to provide power reduction, radiation tolerance, smaller size, and improved reliability over existing non-volatile memory devices. The research encompasses: 1) materials and device design, and 2) fabrication and testing of the devices. The types of memory devices that were investigated are divided into three categories:

Posted in: Briefs, TSP, Electronics & Computers, Semiconductors & ICs, Electronic equipment, Research and development, Reliability


Energy-Filtered Tunnel Transistor: A New Device Concept Toward Extremely Low Energy Consumption Electronics

Device used to study energy-filtered cold electron transport at room temperature: (a) The device structure. (b) Energy diagram for energy-filtered cold electron transport. The quantum well is formed in the conduction band of the Cr203 layer through band bending and a quantum well state serves as an energy filter. Altering the thermal characteristics of semiconductors can prolong battery life.Excessive heat dissipation (or power consumption) of modem integrated circuits is an undesirable effect that imposes substantial limitations on the performance of many electronic devices. For example, the level of heat dissipation /power consumption of smart phones, tablets, and laptops is such that it prohibits a continuous and prolonged operation of these devices, requiring frequent recharging. Large power consumption of electronic devices requires large energy storage in batteries, increasing the battery weights that soldiers carry in their missions or the weights of remote controlled equipment such as unmanned aerial vehicles (UAVs). Therefore, technology that enables electronic devices to operate with extremely small energy consumption promises a broad range of commercial, military and space applications.

Posted in: Briefs, TSP, Electronics & Computers, Transistors, Energy conservation


Epitaxial Growth of Rhenium with Sputtering

What works better – DC or RF sputtering?Epitaxial superconducting films of refractory metals are a promising new template for single crystal tunnel barriers in Josephson junction quantum bit (qubit) devices. In existing Josephson junction qubits, it is believed that the widely-used amorphous AlOx tunnel barriers have undesirable two-state fluctuators. It is speculated that single-crystal tunnel barriers such as sapphire (α-Al2O3) may be free of such decoherence sources.

Posted in: Briefs, Aerospace, Defense, Materials, Computer software and hardware, Conductivity, Metals, Refractory materials


Processing and Characterization of Polycrystalline YAG (Yttrium Aluminum Garnet) Core-Clad Fibers

New techniques could make polycrystalline YAG suitable for use in fiber lasers.YAG-based fiber lasers could offer efficient operation at power levels beyond those achievable in current state-of-the-art silica-based fiber lasers if losses can be minimized. To address this, researchers have investigated creating both single-crystal and polycrystalline YAG fibers. Among the cases reported is the preparation of single-crystal YAG fibers using laser heated pedestal growth (LHPG), which resulted in fiber diameters of 400 μm and optical losses around 1–2 dB/m in the 1–3 μm wavelength range. Single-crystal YAG fibers with diameters of ~ 30 μm have even been reported.

Posted in: Briefs, TSP, Aerospace, Defense, Materials, Finite element analysis, Fiber optics, Lasers, Materials identification


Multi-Scale Analysis of Deformation and Failure in Polycrystalline Titanium Alloys Under High Strain Rates

Developing a crystal plasticity-based computational modeling tool for predicting performance.Extensive use of titanium alloys in critical industrial and military applications, such as compressor blades of jet engines and armor of ground combat vehicles, has motivated researchers to understand, measure and tailor the mechanical properties of these alloys over a wide range of strain rates and temperatures. Of special interest has been the mechanical response of these alloys under high rates of deformation and failure under cyclic/dwell fatigue.

Posted in: Briefs, TSP, Aerospace, Defense, Materials, Aircraft structures, Body panels, Failure modes and effects analysis, Materials properties, Titanium alloys, Military vehicles and equipment