Correlation between luminescence and defects in nonpolar and semipolar InGaN/GaN quantum wells on planar and patterned sapphire substrates

Indium Localization‐Induced Red, Green, and Blue Emissions of Semipolar (11‐22) GaN‐Based Light‐Emitting Diodes

“…[4,5] Therefore, nonpolar and semipolar GaN thin films have been studied to improve emission efficiency. [4][5][6][7][8][9] In addition, as the indium incorporation rate of the (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) GaN film is higher than that of the nonpolar and (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) GaN films, the semipolar (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) GaN is useful for achieving long wavelength (>500 nm) LEDs. [6] Therefore, many research groups have attempted to achieve high-performance green LEDs using semipolar (11)(12)(13)(14)(15)…”

“…[6] Therefore, many research groups have attempted to achieve high-performance green LEDs using semipolar (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) GaN films. [7][8][9][10] However, semipolar (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) GaN-based LEDs grown on m-plane sapphire still exhibit relative low emission efficiency due to poor crystal properties such as high threading dislocations (%10 10 cm À2 ), basal stacking faults (BSFs) (%10 5 cm À1 ), and arrowhead-like surface structures. [9,10] These crystal defects can affect indium incorporation in the InGaN active layer, [11,12] resulting in a significant broadening and band-filling effect of the emission spectrum.…”

“…[9,10] These crystal defects can affect indium incorporation in the InGaN active layer, [11,12] resulting in a significant broadening and band-filling effect of the emission spectrum. Therefore, it is necessary to reduce crystal defects to improve the optical performance of semipolar GaN-based LEDs using the crystal defect reduction methods, such as photoelectrochemical etching, [12] SiN x mask, [7,13] epitaxial layer overgrowth (ELO), [14] patterned sapphire substrate (PSS), [15,16] and so on. Among these crystal defect reduction methods, ELO technique is one of the most effective methods to decrease crystal defects.…”

“…Among these crystal defect reduction methods, ELO technique is one of the most effective methods to decrease crystal defects. [11][12][13][14] In addition, it reported that the hexagonal SiO 2 pattern is more effective in decreasing crystal defect and improving light extraction efficiency in semipolar (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) GaN-based LEDs. [17,18] However, arrowhead-like surface structures were significantly generated by growing a semipolar GaN film due to the anisotropic crystallographic properties, which can form high indium localization that can emit longer wavelengths.…”

“…[21][22][23] However, it is very difficult to achieve a highly uniform and reliable nanostructures for large substrates due to the very complex and expensive nanopatterning and growth process. Therefore, we have systematically studied the effect of arrowhead-like surface structure on the indium localization-induced electroluminescence (EL) properties of semipolar (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) GaN-based LEDs using hexagonal patterns epitaxial lateral overgrowth (HP-ELO) GaN templates with different pattern widths to reduce crystal defects. In addition, we demonstrated the red, green, and blue emissions of a semipolar (11-22) HP-ELO GaN-based LED using different indium localizations in arrowhead-like surface structures.…”