BEGIN:VCALENDAR VERSION:2.0 PRODID:IEEE vTools.Events//EN CALSCALE:GREGORIAN BEGIN:VTIMEZONE TZID:Canada/Eastern BEGIN:DAYLIGHT DTSTART:20220313T030000 TZOFFSETFROM:-0500 TZOFFSETTO:-0400 RRULE:FREQ=YEARLY;BYDAY=2SU;BYMONTH=3 TZNAME:EDT END:DAYLIGHT BEGIN:STANDARD DTSTART:20221106T010000 TZOFFSETFROM:-0400 TZOFFSETTO:-0500 RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=11 TZNAME:EST END:STANDARD END:VTIMEZONE BEGIN:VEVENT DTSTAMP:20220618T153757Z UID:9E804728-1326-43A9-98E8-17112F158971 DTSTART;TZID=Canada/Eastern:20220616T133000 DTEND;TZID=Canada/Eastern:20220616T143000 DESCRIPTION:Abstract : Porous semiconducting nitrides are effectively a new class of semiconducting material\, with properties distinct from the mono lithic nitride layers from which devices from light emitting diodes (LEDs) to high electron mobility transistors are increasingly made. The introduc tion of porosity provides new opportunities to engineer a range of propert ies including refractive index\, thermal and electrical conductivity\, sti ffness and piezoelectricity. Quantum structures may be created within poro us architectures and novel composites may be created via the infiltration of other materials into porous nitride frameworks. A key example of the ap plication of porous nitrides in photonics is the fabrication of high refle ctivity distributed Bragg reflectors (DBRs) from alternating layers of por ous and non-porous GaN. These reflectors are fabricated from epitaxial str uctures consisting of alternating doped and undoped layers\, in which only the conductive\, doped layers are electrochemically etched. Conventionall y\, trenches are formed using a dry-etching process\, penetrating through the multilayer\, and the electrochemical etch then proceeds laterally from the trench sidewalls. The need for these trenches then limits the device designs and manufacturing processes within which the resulting reflectors can be used. We have developed a novel alternative etching process\, which removes the requirement for the dry-etched trenches\, with etching procee ding vertically from the top surface through channels formed at naturally- occurring defects in the crystal structure of GaN. This etch process leave s an undoped top surface layer almost unaltered and suitable for further e pitaxy. This new defect-based etching process provides great flexibility f or the creation of a variety of sub-surface porous architectures on top of which a range of devices may be grown. Whilst DBR structures enable impro ved light extraction from LEDs and the formation of resonant cavities for lasers and single photon sources\, recent development also suggest that th ick\, subs-surface porous layers may enable strain relaxation to help impr ove the efficiency of red microLEDs for augmented reality displays. Meanwh ile\, the option of filling pores in nitride layers with other materials p rovides new opportunities for the integration of nitrides with emerging ph otonic materials\, such as the hybrid-perovskite semiconductors\, with per ovskites encapsulated in porous nitride layers demonstrating greatly impro ved robustness against environmental degradation.\n\nSpeaker(s): Prof. Rac hel A. Oliver\, \n\nRoom: MC603\, McConnell Engineering building\, 3480 Un iversity Street\, H3A 0E9\, Montreal\, Quebec\, Canada\, Virtual: https:// events.vtools.ieee.org/m/312249 LOCATION:Room: MC603\, McConnell Engineering building\, 3480 University Str eet\, H3A 0E9\, Montreal\, Quebec\, Canada\, Virtual: https://events.vtool s.ieee.org/m/312249 ORGANIZER:odile@ieee.org SEQUENCE:8 SUMMARY:IEEE Distinguished Lecture - "New possibilities in nitride photonic s exploiting porosity" by Prof. Rachel A. Oliver URL;VALUE=URI:https://events.vtools.ieee.org/m/312249 X-ALT-DESC:Description: <br /><p><strong>Abstract :</strong> Porous semicon ducting nitrides are effectively a new class of semiconducting material\, with properties distinct from the monolithic nitride layers from which dev ices from light emitting diodes (LEDs) to high electron mobility transisto rs are increasingly made. The introduction of porosity provides new opport unities to engineer a range of properties including refractive index\, the rmal and electrical conductivity\, stiffness and piezoelectricity. Quantum structures may be created within porous architectures and novel composite s may be created via the infiltration of other materials into porous nitri de frameworks.&nbsp\; &nbsp\; A key example of the application of porous n itrides in photonics is the fabrication of high reflectivity distributed B ragg reflectors (DBRs) from alternating layers of porous and non-porous Ga N.&nbsp\; These reflectors are fabricated from epitaxial structures consis ting of alternating doped and undoped layers\, in which only the conductiv e\, doped layers are electrochemically etched. Conventionally\, trenches a re formed using a dry-etching process\, penetrating through the multilayer \, and the electrochemical etch then proceeds laterally from the trench si dewalls.&nbsp\; The need for these trenches then limits the device designs and manufacturing processes within which the resulting reflectors can be used. We have developed a novel alternative etching process\, which remove s the requirement for the dry-etched trenches\, with etching proceeding ve rtically from the top surface through channels formed at naturally-occurri ng defects in the crystal structure of GaN. This etch process leaves an un doped top surface layer almost unaltered and suitable for further epitaxy. This new defect-based etching process provides great flexibility for the creation of a variety of sub-surface porous architectures on top of which a range of devices may be grown.&nbsp\; Whilst DBR structures enable impro ved light extraction from LEDs and the formation of resonant cavities for lasers and single photon sources\, recent development also suggest that th ick\, subs-surface porous layers may enable strain relaxation to help impr ove the efficiency of red microLEDs for augmented reality displays.&nbsp\; Meanwhile\, the option of filling pores in nitride layers with other mate rials provides new opportunities for the integration of nitrides with emer ging photonic materials\, such as the hybrid-perovskite semiconductors\, w ith perovskites encapsulated in porous nitride layers demonstrating greatl y improved robustness against environmental degradation.</p> END:VEVENT END:VCALENDAR