Periodically arranged GaN nanocolumns for the application to visible nanocolumn emitters

Orateur : Katsumi KISHINO (Sophia University, 7-1 Kioicho, Chiyodaku, Tokyo 102-8554, Japan)

The selective area growth (SAG) of GaN nanocolumns with the diameter less than 100 nm was carried out on GaN/sapphire templates through a careful initial nucleation process of nanocolumns at the mask opening. We got the success of the fabrication of orderly arrayed fine nanocolumns down to the diameter of 25 nm, where the nanocolumn period was 100 nm. The growth of highly uniform arrays of GaN nanocolumns with diameters from 122 to 430 nm on Si (111) substrates was demonstrated, where the employment of GaN film templates with flat surfaces obtained using an AlN/GaN superlattice (SL) buffer on Si, contributed to the high-quality SAG of nanocolumns. Although the GaN template included a large number of dislocations (dislocation density 1011 cm-2), the dislocation filtering effect of nanocolumns was enhanced with decreasing nanocolumn diameters. Ti-mak SAG was also carried out on Si substrates employing a thin sputter-deposited AlN nucleation layer, resulting in fabrication of orderly arrayed InGaN/GaN nanocolumn arrays with the photoluminescence emission wavelengths of 455 to 690 nm. Then, we successfully demonstrated a transcription of the grown nanocolumn arrays to another functional supportive conductive CuW carrier, by flip-chip bonding assembly for a high efficiency device. The periodic arrangement of nanocolumns added the photonic crystal effect. Light-diffraction at photonic band edges of Γ points produce the directional radiation beams from nanocolumn LEDs.

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