The origin and evolution of V-defects in InxAl1−xN epilayers grown by metalorganic chemical vapor deposition

Abstract

Articles you may be interested inEffect of indium surfactant on stress relaxation by V-defect formation in GaN epilayers grown by metalorganic chemical vapor deposition J. Appl. Phys. 108, 093511 (2010); 10.1063/1.3487955 Strain effects on In x Al 1 − x N crystalline quality grown on GaN templates by metalorganic chemical vapor deposition J. Appl. Phys. 107, 043515 (2010); 10.1063/1.3305397 Indium migration paths in V-defects of InAlN grown by metal-organic vapor phase epitaxy Appl. Phys. Lett. 95, 071905 (2009); 10.1063/1.3204454 Study of defects evolution in GaN layers grown by metal-organic chemical vapor depositionNear-lattice-matched and highly compressive-strained In x Al 1−x N epilayers were grown on GaN templates by metalorganic chemical vapor deposition. The V-defects associated with screw-component threading dislocations ͑TDs͒ were found in all the In x Al 1−x N layers. Their origin and evolution were investigated through near-lattice-matched In 0.173 Al 0.827 N layers with different thicknesses. Furthermore, small V-defects not associated with TDs were also found in In x Al 1−x N layers with high In composition ͑x = 0.231͒. Stacking mismatch boundaries induced by lattice relaxation in In x Al 1−x N epilayers under large strain is believed to be another mechanism forming V-defects.

Intrinsic degradation mechanism of nearly lattice-matched InAlN layers grown on GaN substrates

“…29,30 When growth is done on a GaN template grown on a foreign substrate, threading dislocations are indeed present in the GaN template with a high density be at the origin of V-defects for InGaN 34 or InAlN layers. [20][21][22][23] Other possibilities for the nucleationof V-defects have been proposed. Dopants were shown to increase the V-defect density in GaN 50 and InAlN layers.…”

“…4 for the InAlN and GaN layers is due to the amorphous glue used during sample preparation that is covering the observed region. However, another contrast is visible in the InAlN layer and not inthe GaNsubstrate, especially when using theg= (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) diffraction condition. The same contrasts are visible in InAlN layers outside the V-defects on the plan-view images of Fig.5 andFig.…”

“…V-defects (or V-pits) are inverted empty pyramids with a hexagonal base, and they aregenerally attributed to threading dislocations. [20][21][22][23] In addition to the abovementioned structural defects, InAlN layers were shown to degrade with increasing thickness. 24 Thus homogeneous layers with a given composition give birth to an upper layer with a higher or a lower indium composition.…”

“…V-defects appearance for 100 nm thick layers observation was done for all the V-defects we observed.This is consistent with the fact that the density of V-defects observed by AFM on this layer is two orders of magnitude larger than the nominal density of threading dislocations.Bothfor InGaN 34 and InAlN layers, [20][21][22][23] V-defects are generally attributed to threading dislocations. However, some authors have also mentioned the presence of V-defects not associated to any threading dislocations in InAlN layers.…”

High-Resolution Electron Microscopy of Semiconductor Heterostructures and Nanostructures

“…Some representative examples in the recent literature can be found for the state-of-the-art, but defective, ternary and quaternary III-Ns studied by some combination of HRTEM, HAADF, EDX, and EELS analyses. In this way, for InAlN nearly lattice matched to GaN, there are reports on horizontal composition separation [128,129], or on In segregation to vertical domain boundaries [140,141] or to surface V-defects [142,143]. For AlGaN, composition modulation [136], phase-separated domains [144] sometimes having tunnel defects and associated dislocations with erratic behaviors [145] have also been measured.…”