Atomic surface structure of antiphase domains in heteroepitaxial GaP films grown on arsenic-terminated Si(100)

The epitaxy of III-V semiconductors on Si(1 0 0) is typically associated with the formation of antiphase domains within the III-V layer. The associated antiphase boundaries constitute planar defects that must be avoided in high-performance devices, or at least prevented from extending into the active region of the device. Here, we present top-view, atomically resolved STM images of thin GaP layers deposited by metalorganic chemical vapor deposition on an As-containing Si(1 0 0) surface. We verify the atomic surface structure, clearly identify phase and antiphase at the surface, and provide high-resolution images of the antiphase boundaries. We show that these boundaries are far from ideal, and are associated with kinks, trenches, and many defects, in particular at the corners of the boundaries. Our work underlines the detrimental effect of the antiphase boundaries, and therefore the necessity for the underlying Si(1 0 0) substrate to be prepared with a near-single-domain surface to avoid antiphase domains in the III-V layer.