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 -