{"46216":{"#nid":"46216","#data":{"type":"news","title":"Radiation-Hardened Microelectronics Could Reduce Spacecraft Weight","body":[{"value":"\u003Cp\u003ESpace environments can deliver a beating to spacecraft electronics. For decades, satellites and other spacecraft have used bulky and expensive shielding to protect vital microelectronics -- microprocessors and other integrated circuits -- from space radiation.\u003C\/p\u003E\n\u003Cp\u003EResearchers at the Georgia Institute of Technology are developing ways to harden the microchips themselves against damage from various types of cosmic radiation.  With funding from NASA and other sponsors, a Georgia Tech team is investigating the use of silicon-germanium (SiGe) to create microelectronic devices that are intrinsically resistant to space-particle bombardment.\n\u003C\/p\u003E\n\u003Cp\u003EKey to the investigation is determining exactly what happens inside a device at the instant a particle hits, says principal investigator John D. Cressler, who is a Ken Byers Professor in the Georgia Tech School of Electrical and Computer Engineering. \n\u003C\/p\u003E\n\u003Cp\u003E\u0022Cosmic radiation can go right through the spacecraft, and right through electronics on the way, generating charge inside the device that can cause electronic systems to produce errors or even die,\u0022 Cressler said.  \u0022There\u0027s a lot of interest in improved hardening capabilities from NASA, the Department of Defense and communications companies, because anything that flies into space has to withstand the effects of this radiation.\u0022\n\u003C\/p\u003E\n\u003Cp\u003ESilicon-germanium holds major promise for this application, he adds. SiGe alloys combine silicon, the most common microchip material, with germanium, at nanoscale dimensions.  The result is a material that offers important gains in toughness, speed and flexibility.\n\u003C\/p\u003E\n\u003Cp\u003EAny space vehicle, from NASA spacecraft and military vehicles to communications and global positioning system (GPS) satellites, must contend with two principal types of cosmic radiation. \n\u003C\/p\u003E\n\u003Cp\u003E-- \u003Cstrong\u003EIonizing radiation \u003C\/strong\u003Eincludes ubiquitous particles such as electrons and protons that are relatively high in energy but not deeply penetrating.  A moderate amount of metal shielding can reduce their destructive effect, but such protection increases a space vehicle\u0027s launch weight.  \n\u003C\/p\u003E\n\u003Cp\u003E-- \u003Cstrong\u003EGalactic cosmic rays \u003C\/strong\u003Einclude heavy ions and other extremely high-energy particles.   It is virtually impossible to protect against these dangers.\n\u003C\/p\u003E\n\u003Cp\u003EFaced with damaging radiation, engineers have for decades augmented shielding with a circuit-design technique called \u0022triple modular redundancy.\u0022 This approach utilizes three copies of each circuit, all tied into logic circuitry at one end. If one copy of the circuit is corrupted by cosmic radiation and begins producing bad data, the logic circuit opts for the matching data produced by the other two circuits.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022The problem with this approach is that it requires three times the overhead in power, real-estate and cost,\u0022 Cressler said.\n\u003C\/p\u003E\n\u003Cp\u003EOther traditional circuit-protecting techniques have included the hardening-by-process method.  In this approach, integrated circuits are produced using special processes that harden the chips against radiation damage.  The problem is this processing generally increases chip costs by 10 to 50 times.  \n\u003C\/p\u003E\n\u003Cp\u003EAs a result, the space community is eager to find ways to produce space-hardened microelectronic devices using only everyday commercial chip-making technologies, Cressler says.  The savings in cost, size and weight could be very significant.\n\u003C\/p\u003E\n\u003Cp\u003ESilicon-germanium is a top candidate for this application because it has intrinsic immunity to many types of radiation. The catch is that, like other materials, SiGe cannot stand up to the extremely destructive heavy ions present in galactic cosmic rays.\n\u003C\/p\u003E\n\u003Cp\u003EAt least, not yet.\n\u003C\/p\u003E\n\u003Cp\u003ECressler\u0027s team is analyzing exactly what happens inside a SiGe device when it\u0027s subjected to the type of energy found in heavy ions. Using sophisticated new equipment, including an extremely high-speed oscilloscope, researchers can capture details of particle-strike events that last only trillionths of a second (picoseconds).\n\u003C\/p\u003E\n\u003Cp\u003EWorking with NASA and the U.S. Naval Research Laboratory, Cressler is using an ultrafast laser to inject current into a silicon-germanium transistor.  The aim is to emulate the effect of a heavy-ion strike in space.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022When I shine a laser on the device, it generates a pulse of current that may only last for a few picoseconds,\u0022 Cressler said. \u0022Capturing the dynamics of that process -- what it looks like in time and in its magnitudes -- is important and challenging.\u0022\n\u003C\/p\u003E\n\u003Cp\u003ECressler\u0027s investigation also involves firing actual ions at SiGe circuits. Using a focused ion microbeam at the Sandia National Laboratories, the Georgia Tech team can aim a single heavy ion at a given point on a device and capture those results as well.\n\u003C\/p\u003E\n\u003Cp\u003EThe ultimate aim is to alter silicon-germanium devices and circuits in ways that will make them highly resistant to nearly all cosmic radiation, including heavy ions, without adding overhead.\n\u003C\/p\u003E\n\u003Cp\u003EObserving actual particle impacts in real time is key, Cressler says. Detailed computer 3-D models of particle strikes on SiGe devices and circuits -- created with sophisticated numerical simulation techniques -- have already been developed.  But until researchers can compare these models to actual observed data, they can\u0027t be sure the models are correct. \n\u003C\/p\u003E\n\u003Cp\u003E\u0022If we get good fidelity between the two,\u0022 he added, \u0022then we\u0027ve know we have a good understanding of the physics.\u0022 \n\u003C\/p\u003E\n\u003Cp\u003EStep two, he adds, will involve using that information to design devices and circuits that are highly immune to radiation. \n\u003C\/p\u003E\n\u003Cp\u003E\u0022One of the holy grails in this field is getting sufficient radiation hardness without resorting to any of the high overhead schemes such as shielding, process hardening, or triple modular redundancy,\u0022 he said.  \u0022And, in fact, we are closing in on that goal, using SiGe electronics.\u0022\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EResearch News \u0026amp; Publications Office\u003Cbr \/\u003E\nGeorgia Institute of Technology\u003Cbr \/\u003E\n75 Fifth Street, N.W., Suite 100\u003Cbr \/\u003E\nAtlanta, Georgia  30308  USA\u003C\/strong\u003E\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EMedia Relations Contacts\u003C\/strong\u003E: John Toon (404-894-6986); E-mail: (\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E) or Abby Vogel (404-385-3364); E-mail: (\u003Ca href=\u0022mailto:avogel@gatech.edu\u0022\u003Eavogel@gatech.edu\u003C\/a\u003E).\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003ETechnical Contact\u003C\/strong\u003E: John Cressler (404-894-5161); E-mail: (\u003Ca href=\u0022mailto:john.cressler@ece.gatech.edu\u0022\u003Ejohn.cressler@ece.gatech.edu\u003C\/a\u003E).\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E: Rick Robinson\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":[{"value":"Silicon-Germanium Circuits Could Also Cut Costs"}],"field_summary":[{"value":"Researchers are developing new ways to harden microelectronics for space applications using silicon-germanium, an alloy that is intrinsically resistant to space-particle bombardment.","format":"limited_html"}],"field_summary_sentence":[{"value":"Researchers are developing new ways to harden circuits for space"}],"uid":"27303","created_gmt":"2009-09-28 00:00:00","changed_gmt":"2016-10-08 03:03:14","author":"John Toon","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2009-09-28T00:00:00-04:00","iso_date":"2009-09-28T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"46217":{"id":"46217","type":"image","title":"Studying silicon-germanium","body":null,"created":"1449174358","gmt_created":"2015-12-03 20:25:58","changed":"1475894412","gmt_changed":"2016-10-08 02:40:12","alt":"Studying silicon-germanium","file":{"fid":"101022","name":"tly64084.jpg","image_path":"\/sites\/default\/files\/images\/tly64084.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/tly64084.jpg","mime":"image\/jpeg","size":1432913,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/tly64084.jpg?itok=Q0n_Ka_V"}},"46218":{"id":"46218","type":"image","title":"John Cressler","body":null,"created":"1449174358","gmt_created":"2015-12-03 20:25:58","changed":"1475894412","gmt_changed":"2016-10-08 02:40:12","alt":"John Cressler","file":{"fid":"101023","name":"tgr64084.jpg","image_path":"\/sites\/default\/files\/images\/tgr64084.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/tgr64084.jpg","mime":"image\/jpeg","size":1893724,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/tgr64084.jpg?itok=2HTyaLTI"}},"46219":{"id":"46219","type":"image","title":"Studying silicon-germanium","body":null,"created":"1449174358","gmt_created":"2015-12-03 20:25:58","changed":"1475894412","gmt_changed":"2016-10-08 02:40:12","alt":"Studying silicon-germanium","file":{"fid":"101024","name":"tfh64084.jpg","image_path":"\/sites\/default\/files\/images\/tfh64084.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/tfh64084.jpg","mime":"image\/jpeg","size":1421894,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/tfh64084.jpg?itok=-mcphuBD"}}},"media_ids":["46217","46218","46219"],"related_links":[{"url":"http:\/\/www.ece.gatech.edu\/","title":"School of Electrical and Computer Engineering"},{"url":"http:\/\/www.ece.gatech.edu\/faculty-staff\/fac_profiles\/bio.php?id=123","title":"John Cressler"}],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"136","name":"Aerospace"},{"id":"145","name":"Engineering"},{"id":"149","name":"Nanotechnology and Nanoscience"},{"id":"135","name":"Research"}],"keywords":[{"id":"2832","name":"microelectronics"},{"id":"1963","name":"particles"},{"id":"170841","name":"silicon-germanium"},{"id":"167146","name":"space"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cstrong\u003EJohn Toon\u003C\/strong\u003E\u003Cbr \/\u003EResearch News \u0026amp; Publications Office\u003Cbr \/\u003E\u003Ca href=\u0022http:\/\/www.gatech.edu\/contact\/index.html?id=jt7\u0022\u003EContact John Toon\u003C\/a\u003E\u003Cbr \/\u003E\u003Cstrong\u003E404-894-6986\u003C\/strong\u003E","format":"limited_html"}],"email":["jtoon@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}