{"249401":{"#nid":"249401","#data":{"type":"news","title":"ASU, Georgia Tech Create Breakthrough for Solar Cell Efficiency","body":[{"value":"\u003Cp\u003EDid you know that crystals form the basis for the penetrating icy blue glare of car headlights and could be fundamental to the future in solar energy technology?\u003C\/p\u003E\u003Cp\u003ECrystals are at the heart of diodes. Not the kind you might find in quartz, formed naturally, but manufactured to form alloys, such as indium gallium nitride or InGaN. This alloy forms the light emitting region of LEDs, for illumination in the visible range, and of laser diodes (LDs) in the blue-UV range.\u003C\/p\u003E\u003Cp\u003EResearch into making better crystals, with high crystalline quality, light emission efficiency and luminosity, is also at the heart of studies being done at Arizona State University by Research Scientist Alec Fischer and Doctoral Candidate Yong Wei in Professor Fernando Ponce\u2019s group in the Department of Physics.\u003C\/p\u003E\u003Cp\u003EIn an article recently published in the journal \u003Cem\u003EApplied Physics Letters\u003C\/em\u003E, the ASU group, in collaboration with a scientific team led by Professor Alan Doolittle at the Georgia Institute of Technology, has just revealed the fundamental aspect of a new approach to growing InGaN crystals for diodes, which promises to move photovoltaic solar cell technology toward record-breaking efficiencies.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ESolar Energy Crystallizes\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EThe InGaN crystals are grown as layers in a sandwich-like arrangement on sapphire substrates.\u0026nbsp; Typically, researchers have found that the atomic separation of the layers varies; a condition that can lead to high levels of strain, breakdowns in growth, and fluctuations in the alloy\u2019s chemical composition.\u003C\/p\u003E\u003Cp\u003E\u201cBeing able to ease the strain and increase the uniformity in the composition of InGaN is very desirable,\u201d says Ponce, \u201cbut difficult to achieve. Growth of these layers is similar to trying to smoothly fit together two honeycombs with different cell sizes, where size difference disrupts a periodic arrangement of the cells.\u201d\u003C\/p\u003E\u003Cp\u003EAs outlined in their publication, the authors developed an approach where pulses of molecules were introduced to achieve the desired alloy composition. The method, developed by Doolittle, is called metal-modulated epitaxy. \u201cThis technique allows an atomic layer-by-layer growth of the material,\u201d says Ponce.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003EAnalysis of the atomic arrangement and the luminosity at the nanoscale level was performed by Fischer, the lead author of the study, and Wei. Their results showed that the films grown with the epitaxy technique had almost ideal characteristics and revealed that the unexpected results came from the strain relaxation at the first atomic layer of crystal growth.\u003C\/p\u003E\u003Cp\u003E\u201cDoolittle\u2019s group was able to assemble a final crystal that is more uniform and whose lattice structures match up\u2026resulting in a film that resembles a perfect crystal,\u201d says Ponce. \u201cThe luminosity was also like that of a perfect crystal. Something that no one in our field thought was possible.\u201d\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EThe Perfect Solar Cell?\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EThe ASU and Georgia Tech team\u2019s elimination of these two seemingly insurmountable defects (non-uniform composition and mismatched lattice alignment) ultimately means that LEDs and solar photovoltaic products can now be developed that have much higher, efficient performance.\u003C\/p\u003E\u003Cp\u003E\u201cWhile we are still a ways off from record-setting solar cells, this breakthrough could have immediate and lasting impact on light emitting devices and could potentially make the second most abundant semiconductor family, III-Nitrides, a real player in the solar cell field,\u201d says Doolittle. Doolittle\u2019s team at Georgia Tech\u0027s School of Electrical and Computer Engineering also included Michael Moseley and Brendan Gunning. A patent is pending for the new technology.\u003C\/p\u003E\u003Cp\u003EThe collaboration was made possible by ASU\u2019s Engineering Research Center for Quantum Energy and Sustainable Solar Technologies (QESST) funded by National Science Foundation and U.S. Department of Energy. The center, which brought the two research groups together, is directed by ASU Professor Christiana Honsberg of the Ira A. Fulton Schools of Engineering. Designed to increase photovoltaic electricity and help create devices that are scalable to commercial production, the center has built partnerships with leading solar energy companies and fueled collaborations between many of the notable universities in the U.S., Asia, Europe and Australia. The center also serves as a platform for educational opportunities for students including new college courses, partnerships with local elementary schools and public engagement events to raise awareness of the exciting challenges of harnessing the sun to power our world.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003E\u003Cbr \/\u003E\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ENOTE:\u003C\/strong\u003E Pending U.S. patent application # US20130244408, \u201cSystems and Methods For Growing A Non-Phase Separated Group-III Nitride Semiconductor Alloy.\u201d\u0026nbsp; Inventors are Alan Doolittle and Michael Moseley.\u0026nbsp; The published application can be found online at \u003Ca href=\u0022http:\/\/appft.uspto.gov\/netacgi\/nph-Parser?Sect1=PTO1\u0026amp;Sect2=HITOFF\u0026amp;d=PG01\u0026amp;p=1\u0026amp;u=%2Fnetahtml%2FPTO%2Fsrchnum.html\u0026amp;r=1\u0026amp;f=G\u0026amp;l=50\u0026amp;s1=%2220130244408%22.PGNR.\u0026amp;OS=DN\/20130244408\u0026amp;RS=DN\/20130244408\u0022\u003Ehttp:\/\/appft.uspto.gov\/netacgi\/nph-Parser?Sect1=PTO1\u0026amp;Sect2=HITOFF\u0026amp;d=PG01\u0026amp;p=1\u0026amp;u=%2Fnetahtml%2FPTO%2Fsrchnum.html\u0026amp;r=1\u0026amp;f=G\u0026amp;l=50\u0026amp;s1=%2220130244408%22.PGNR.\u0026amp;OS=DN\/20130244408\u0026amp;RS=DN\/20130244408\u003C\/a\u003E or \u003Ca href=\u0022https:\/\/www.google.com\/patents\/US20130244408?dq=20130244408\u0026amp;hl=en\u0026amp;sa=X\u0026amp;ei=p1plUt3YK4XU9ASc2YAQ\u0026amp;ved=0CDcQ6AEwAA\u0022\u003Ehttps:\/\/www.google.com\/patents\/US20130244408?dq=20130244408\u0026amp;hl=en\u0026amp;sa=X\u0026amp;ei=p1plUt3YK4XU9ASc2YAQ\u0026amp;ved=0CDcQ6AEwAA\u003C\/a\u003E.\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThis story was written by Peggy Coulombe, media relations officer and director of Academic Communications for the College of Liberal Arts and Studies at Arizona State University.\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":[{"value":"New Atomic Layer-by-Layer InGaN Technology Offers Perfect Crystal?"}],"field_summary":[{"value":"\u003Cp\u003EIn an article recently published in the journal Applied Physics Letters, a research team from Arizona State University and the Georgia Institute of Technology has just revealed the fundamental aspect of a new approach to growing InGaN crystals for diodes, which promises to move photovoltaic solar cell technology toward record-breaking efficiencies.\u003Cbr \/\u003E\u003Cbr \/\u003E\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":"","uid":"27241","created_gmt":"2013-10-28 13:58:59","changed_gmt":"2016-10-08 03:15:14","author":"Jackie Nemeth","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2013-10-28T00:00:00-04:00","iso_date":"2013-10-28T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"249411":{"id":"249411","type":"image","title":"Atomic arrangement at a relaxed InGaN\/GaN interface","body":null,"created":"1449243795","gmt_created":"2015-12-04 15:43:15","changed":"1475894929","gmt_changed":"2016-10-08 02:48:49","alt":"Atomic arrangement at a relaxed InGaN\/GaN interface","file":{"fid":"198056","name":"fig_5.jpg","image_path":"\/sites\/default\/files\/images\/fig_5_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/fig_5_0.jpg","mime":"image\/jpeg","size":133856,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/fig_5_0.jpg?itok=2sGYIfHj"}}},"media_ids":["249411"],"related_links":[{"url":"http:\/\/www.gatech.edu\/","title":"Georgia Tech"},{"url":"http:\/\/www.asu.edu\/","title":"Arizona State University"},{"url":"http:\/\/www.ece.gatech.edu\/faculty-staff\/fac_profiles\/bio.php?id=28","title":"W. Alan Doolittle"},{"url":"http:\/\/physics.asu.edu\/people\/faculty\/fernando-ponce","title":"Fernando Ponce"},{"url":"http:\/\/qesst.asu.edu\/","title":"Quantum Energy and Sustainable Solar Technologies, An NSF-DOE Engineering Research Center"}],"groups":[{"id":"1255","name":"School of Electrical and Computer Engineering"}],"categories":[{"id":"134","name":"Student and Faculty"},{"id":"144","name":"Energy"},{"id":"145","name":"Engineering"},{"id":"154","name":"Environment"},{"id":"149","name":"Nanotechnology and Nanoscience"},{"id":"135","name":"Research"},{"id":"150","name":"Physics and Physical Sciences"}],"keywords":[{"id":"1159","name":"Alan Doolittle"},{"id":"78411","name":"Applied Physics Letters"},{"id":"78371","name":"Arizona State University"},{"id":"78381","name":"Department of Physics"},{"id":"78391","name":"Fernando Ponce"},{"id":"246","name":"Georgia Institute of Technology"},{"id":"78401","name":"InGaN crystals"},{"id":"166855","name":"School of Electrical and Computer Engineering"}],"core_research_areas":[{"id":"39451","name":"Electronics and Nanotechnology"},{"id":"39531","name":"Energy and Sustainable Infrastructure"},{"id":"39471","name":"Materials"}],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EJackie Nemeth\u003C\/p\u003E\u003Cp\u003ESchool of Electrical and Computer Engineering\u003C\/p\u003E\u003Cp\u003E404-894-2906\u003C\/p\u003E\u003Cp\u003E\u003Ca href=\u0022mailto:jackie.nemeth@ece.gatech.edu\u0022\u003Ejackie.nemeth@ece.gatech.edu\u003C\/a\u003E\u003C\/p\u003E","format":"limited_html"}],"email":["jackie.nemeth@ece.gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}