Abstract：GaN with hexagonal pyramids is fabricated using the photo-assisted electroless chemical etching method. Defective areas of the GaN substrate are selectively etched in a mixed solution of KOH and K2S2O8 under ultraviolet illumination, producing submicron-sized pyramids. Hexagonal pyramids on the etched GaN with well-defined {1011} facets and very sharp tips are formed. High-resolution x-ray diffraction shows that etched GaN with pyramids has a higher crystal quality, and micro-Raman spectra reveal a tensile stress relaxation in GaN with pyramids compared with normal GaN. The cathodoluminescence intensity of GaN after etching is significantly increased by three times, which is attributed to the reduction in the internal reflection, high-quality GaN with pyramids and the Bragg effect.
[1] Fu D J, Park Y S, Panin G N and Kang T W 2005 Jpn. J. Appl. Phys.44 L342 [2] Ward B L, Nam O H, Hartman J D, English S L, McCarson B L, Schlesser R, Sitar Z, Davis R F and Nemanich R J 1998 J. Appl. Phys.84 5238 [3] Jiang H X, Lin J Y, Zeng K C and Yang W 1999 Appl. Phys. Lett.75 763 [4] Fujii T, Gao Y, Sharma R, Hu E L, DenBaars S P and Nakamura S 2004 Appl. Phys. Lett.84 855 [5] Tachibana K, Someya T, Ishida S and Arakawa Y 2000 Appl. Phys. Lett.76 3212 [6] Jo D W, Ok J E, Yun W, Jeon H S, Lee G S, Jung S G, Bae S M, Ahn H S and Yang M 2012 Jpn. J. Appl. Phys.51 01AF03 [7] Kozawa T, Ohwaki T, Taga Y and Sawaki N 1999 Appl. Phys. Lett.75 3330 [8] Cho Y H, Kim H M, Kang T W, Song J J and Yang W 2002 Appl. Phys. Lett.80 1141 [9] Zeng K C, Lin J Y, Jiang H X and Yang W 1999 Appl. Phys. Lett.74 1227 [10] Liu Q K, Hoffmann A, Siegle H, Kaschner A, Thomsen C, Christen J and Bertram F 1999 Appl. Phys. Lett.74 3122 [11] Kim T, Kim J, Yang M S, Lee S, Park Y, Chung U I and Cho Y 2010 Appl. Phys. Lett.97 241111 [12] Kim T, Kim J, Yang M, Lee S, Park Y and Chung U 2010 Conference on Lasers and Electro-Optic (California, San Jose 16–21 May 2010) CTuNN2 [13] Kim T, Kim J, Yang M, Lee S, Park Y, Ko Y and Cho Y 2011 Conference on Lasers and Electro-Optic (Maryland, Baltimore 1–6 May 2011) CMA4 [14] Kim T, Kim J, Yang M, Park Y, Chung U I, Ko Y and Cho Y 2012 Conference on Lasers and Electro-Optic (Maryland, Baltimore 6–11 May 2012) ATh5A.5 [15] Bardwell J A, Foulds I G, Webb J B, Tang H, Fraser J, Moisa S and Rolfe S J 1999 J. Electron. Mater.28 L24 [16] Kolthoff I M and Miller I K 1951 J. Am. Chem. Soc.73 3055 [17] Gomer R 1961 Field Emission and Field Ionization (Cambridge: Harvard University Press) [18] Li S F, Fuendling S, Wang X, Merzsch S, Al-Suleiman M A M, Wei J D, Wehmann H H, Waag A, Bergbauer W and Strassburg M 2011 Cryst. Growth Des.11 1573 [19] Park S H 2002 J. Appl. Phys.91 9904 [20] Hartono H, Soh C B, Chow S Y, Chua S J and Fitzgerald E 2007 Appl. Phys. Lett.90 171917 [21] Tripathy S, Chua S J, Chen P and Miao Z L 2002 J. Appl. Phys.92 3503 [22] Schnitzer I, Yablonovitch E, Caneau C, Gmitter T J and Scherer A 1993 Appl. Phys. Lett.63 2174 [23] Windisch R, Dutta B, Kuijk M, Knobloch A, Meinlschmidt S, Schoberth S, Kiesel P, Borghs G, Do?hler G H and Heremans P 2000 IEEE Trans. Electron Devices47 1492
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