AlGaN epitaxial lateral overgrowth on Ti-evaporated GaN/sapphire substrate

TEM investigations on growth interrupted samples for the correlation of the dislocation propagation and growth mode variations in AlGaN deposited on SiN interlayers

“…We could observe the formation of basal-plane stacking faults (BSFs) in areas correlating with specific regions in our growth model. The HRTEM image from the [11][12][13][14][15][16][17][18][19][20] zone in Fig. 12(a) shows an accumulation of BSFs directly above the SiN x interface in a region of high defect reduction, whereas the AlGaN overlayer is free of BSFs in regions more than 30 nm away from the SiN x interface.…”

“…12. HRTEM images of sample S1 from the [11][12][13][14][15][16][17][18][19][20] zone in the range of the SiN x interface. The images show the formation of basal-plane stacking faults directly above the SiN x mask.…”

“…Especially a-type threading dislocations (TDs) are responsible for still high dislocation densities in the 10 10 cm À 2 range, which can act as non-radiative recombination centres and thus lower the efficiency and the lifetime of the optoelectronic device [7][8][9]. One method to reduce the TD density in (Al,Ga)N layers is the use of epitaxial lateral overgrowth (ELO), which is widely used to grow high quality GaN layers [10,11] and has also been adapted to AlGaN [12]. However ELO is combined with typical drawbacks, such as complex ex-situ masking procedures and the presence of TDs in the window regions.…”

High quality AlGaN epilayers grown on sapphire using SiN interlayers

“…Different ELO techniques with ex situ substrate patterning are widely used to grow high quality GaN layers [4][5][6] and have also been adapted to AlGaN layers [7,8]. However, long ex situ masking procedures and the presence of localized TDs in the window regions are typical drawbacks of ELO.…”

Growth of GaN Layer on Patterned Al/Ti Metal Mask by Metal–Organic Chemical Vapor Deposition

“…11) Recently, newly suggested approaches have been introduced, such as using the tungsten (W) and titanium (Ti) for the patterned masking layer. 8,12) The intermetallic phase of the Al/Ti alloy can be considered as a promising material for a new masking layer owing to its high-temperature applications 13) and high reflectance related to the enhancement of light extraction efficiency (LEE) in LEDs. 14) In this study, a high-quality GaN layer was grown by metal-organic chemical vapor deposition (MOCVD) on a stripe-patterned GaN template with a metal mask.…”