Direct atomic imaging of antiphase boundaries and orthotwins in orientation-patterned GaAs

Abstract

We use transmission electron microscopy to study orientation-patterned GaAs layers very attractive for applications in terahertz and infrared frequency conversion devices. We observe regularly distributed inversion domains separated by inversion boundaries, together with undesirable microtwin defects originating at these boundaries. Atomic resolution aberration-corrected scanning transmission electron microscopy allowed us to resolve the GaAs dumbbells leading to a direct determination of the growth polarity of particular domains and determination of the alternating Ga-Ga and As-As bonds at the {110}-type antiphase boundary planes. We also determined observed microtwins as rotation twins called orthotwins, the defect that can cause optical losses.

Antiphase structures in a periodically inverted GaAs/AlGaAs waveguide investigated by transmission electron microscopy

“…In addition to the Ge interlayer and Al 0.1 Ga 0.9 As=GaAs interface, artificial (011) domain boundaries are clearly observed as etched planar defects. The (011) domain boundaries are reported to be antiphase boundaries composed of alternating Ga-Ga and As-As bonds 30) as shown in Fig. 2(c).…”