Resolving alternating stress gradients and dislocation densities across AlxGa1-xN multilayer structures on Si(111)
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In: Applied physics letters, Vol. 111.2017, No. 16, 16.10.2017, p. 162103.
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TY - JOUR
T1 - Resolving alternating stress gradients and dislocation densities across AlxGa1-xN multilayer structures on Si(111)
AU - Reisinger, Michael
AU - Tomberger, M.
AU - Zechner, J
AU - Daumiller, I.
AU - Sartory, B
AU - Ecker, W
AU - Keckes, Jozef
AU - Lechner, Rainer T.
PY - 2017/10/16
Y1 - 2017/10/16
N2 - Gradients of residual stresses and crystal qualities across a 2 μm thick AlN/Al0.32Ga0.68N/GaN/Al0.17Ga0.83N multilayer stack deposited on Si (111) were evaluated by combining the following techniques: High-resolution X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), high resolution transmission electron microscopy, and ion beam layer removal method (ILR) with 100 nm depth resolution. ILR reveals the alternating stress profiles, which are related to sublayer dislocation-density gradients. The laboratory XRD confirms the derived mean stress values, the presence of stress gradients within the sublayers, and decreasing average sublayer threading dislocation-densities across the heterostructure. Additionally, the decreasing dislocation-densities within the individual sublayers are visualized by STEM. The documented stepwise improved crystal quality enables the formation of a highly tensile stressed 20 nm thick Al0.17Ga0.83N top barrier layer, resulting in a pseudomorphic GaN/Al0.17Ga0.83N interface.
AB - Gradients of residual stresses and crystal qualities across a 2 μm thick AlN/Al0.32Ga0.68N/GaN/Al0.17Ga0.83N multilayer stack deposited on Si (111) were evaluated by combining the following techniques: High-resolution X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), high resolution transmission electron microscopy, and ion beam layer removal method (ILR) with 100 nm depth resolution. ILR reveals the alternating stress profiles, which are related to sublayer dislocation-density gradients. The laboratory XRD confirms the derived mean stress values, the presence of stress gradients within the sublayers, and decreasing average sublayer threading dislocation-densities across the heterostructure. Additionally, the decreasing dislocation-densities within the individual sublayers are visualized by STEM. The documented stepwise improved crystal quality enables the formation of a highly tensile stressed 20 nm thick Al0.17Ga0.83N top barrier layer, resulting in a pseudomorphic GaN/Al0.17Ga0.83N interface.
U2 - 10.1063/1.4998694
DO - 10.1063/1.4998694
M3 - Article
VL - 111.2017
SP - 162103
JO - Applied physics letters
JF - Applied physics letters
SN - 0003-6951
IS - 16
ER -