NASA GRC Wide Bandgap Electronics Technical Advancement Issues for Consideration by Dept. of Energy

What is needed to manufacture quality SiC power switches for space applications within the next 5 years? How can the proposed Dept. of Energy Consortium help achieve this goal

Method for Providing Semiconductors Having Self-Aligned Ion Implant

A method is disclosed that provides a self-aligned nitrogen-implant particularly suited for a Junction Field Effect Transistor (JFET) semiconductor device preferably comprised of a silicon carbide (SiC). This self-aligned nitrogen-implant allows for the realization of durable and stable electrical functionality of high temperature transistors such as JFETs. The method implements the self-aligned nitrogen-implant having predetermined dimensions, at a particular step in the fabrication process, so that the SiC junction field effect transistors are capable of being electrically operating continuously at 500.degree. C. for over 10,000 hours in an air ambient with less than a 10% change in operational transistor parameters

Are spin junction transistors suitable for signal processing?

A number of spintronic junction transistors, that exploit the spin degree of freedom of an electron in addition to the charge degree of freedom, have been proposed to provide simultaneous non-volatile storage and signal processing functionality. Here, we show that some of these transistors unfortunately may not have sufficient voltage and current gains for signal processing. This is primarily because of a large output ac conductance and poor isolation between input and output. The latter also hinders unidirectional propagation of logic signal from the input of a logic gate to the output. Other versions of these transistors appear to have better gain and isolation, but not better than those of a conventional transistor. Therefore, these devices may not improve state-of-the-art signal processing capability, although they may provide additional functionality by offering non-volatile storage. They may also have niche applications in non-linear circuits

Method for Providing Semiconductors Having Self-Aligned Ion Implant

A method is disclosed that provides a self-aligned nitrogen-implant particularly suited for a Junction Field Effect Transistor (JFET) semiconductor device preferably comprised of a silicon carbide (SiC). This self-aligned nitrogen-implant allows for the realization of durable and stable electrical functionality of high temperature transistors such as JFETs. The method implements the self-aligned nitrogen-implant having predetermined dimensions, at a particular step in the fabrication process, so that the SiC junction field effect transistors are capable of being electrically operating continuously at 500.degree. C. for over 10,000 hours in an air ambient with less than a 10% change in operational transistor parameters

Heterostructure unipolar spin transistors

We extend the analogy between charge-based bipolar semiconductor electronics and spin-based unipolar electronics by considering unipolar spin transistors with different equilibrium spin splittings in the emitter, base, and collector. The current of base majority spin electrons to the collector limits the performance of ``homojunction'' unipolar spin transistors, in which the emitter, base, and collector all are made from the same magnetic material. This current is very similar in origin to the current of base majority carriers to the emitter in homojunction bipolar junction transistors. The current in bipolar junction transistors can be reduced or nearly eliminated through the use of a wide band gap emitter. We find that the choice of a collector material with a larger equilibrium spin splitting than the base will similarly improve the device performance of a unipolar spin transistor. We also find that a graded variation in the base spin splitting introduces an effective drift field that accelerates minority carriers through the base towards the collector.Comment: 9 pages, 2 figure

Silicon Carbide Technology

Silicon carbide based semiconductor electronic devices and circuits are presently being developed for use in high-temperature, high-power, and high-radiation conditions under which conventional semiconductors cannot adequately perform. Silicon carbide's ability to function under such extreme conditions is expected to enable significant improvements to a far-ranging variety of applications and systems. These range from greatly improved high-voltage switching for energy savings in public electric power distribution and electric motor drives to more powerful microwave electronics for radar and communications to sensors and controls for cleaner-burning more fuel-efficient jet aircraft and automobile engines. In the particular area of power devices, theoretical appraisals have indicated that SiC power MOSFET's and diode rectifiers would operate over higher voltage and temperature ranges, have superior switching characteristics, and yet have die sizes nearly 20 times smaller than correspondingly rated silicon-based devices [8]. However, these tremendous theoretical advantages have yet to be widely realized in commercially available SiC devices, primarily owing to the fact that SiC's relatively immature crystal growth and device fabrication technologies are not yet sufficiently developed to the degree required for reliable incorporation into most electronic systems. This chapter briefly surveys the SiC semiconductor electronics technology. In particular, the differences (both good and bad) between SiC electronics technology and the well-known silicon VLSI technology are highlighted. Projected performance benefits of SiC electronics are highlighted for several large-scale applications. Key crystal growth and device-fabrication issues that presently limit the performance and capability of high-temperature and high-power SiC electronics are identified

Technical Primer on Design and SPICE Modeling of Circuits for NASA Glenn SiC JFET IC Version 12 Prototype Wafer Run Part 1: SiC JFET Behavior and SPICE Modeling

This presentation illustratively communicates how to SPICE model silicon carbide (SiC) SiC junction field effect transistors (JFETs) for designing circuits for NASA GRC's upcoming prototype fabrication of SiC JFET IC Version 12