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(Invited) Fully Porous GaN p-n Junctions Fabricated by Chemical Vapor Deposition: A Green Technology towards More Efficient LEDs
Through chemical vapour deposition (CVD) [1], we have shown that it was possible to produce nanoporous GaN without any secondary etching or chemical post-growth treatment in order to generate the porosity, present only on the (0001) face of the material, providing a green approach for the production of porous GaN. These nanoporous GaN particles can be deposited on different substrates, including boron nitride, silicon, sapphire and SiC, obtaining porous particles with a low density of defects, as revealed by the emission arising only from the band-edge of the particles obtained in the cathodoluminescence studies [2]. By using this methodology of growth, we demonstrated the fabrication of low resistivity ohmic Pt and Au metallic contacts on porous n-type GaN by the formation of intermetallic seed layers through the vapour-solid-solid (VSS) mechanism [3]. Also, we have been able to develop p-type porous GaN by doping with Mg, with a charge carrier concentration of the order of 1018 cm-3 [4].
Through the careful selection of the substrate it is possible to produce porous GaN epitaxial layers [5] that allow for the fabrication of high quality partially and fully porous GaN rectifying p-n junctions, through a 2 step CVD process, and show their behaviour as diodes with effective uniform conduction [6]. These porous junctions have potential applications in high brightness unencapsulated LEDs with enhanced light emitting properties and high surface area sensors with improved sensitivity.
[1] Carvajal & Rojo, Crystal Growth Des. 9 (2009) 320
[2] Carvajal et al., Microsc. Microanal. 18 (2012) 905
[3] Bilousov et al., ACS Appl. Mater. Interfaces 4 (2012) 6927
[4] Bilousov et al., Appl. Phys. Lett. 103 (2013) 112103
[5] Bilousov et al., CrystEngComm 16 (2014) 10255
[6] Bilousov et al., ACS Appl. Mater. Interfaces 6 (2014) 17954