Pseudomorphic growth and strain relaxation of α-Zn3P2 on GaAs(001) by molecular beam epitaxy

Tetragonal zinc phosphide (α-Zn3P2) was grown pseudomorphically, by compound-source molecular-beam epitaxy on GaAs(001). The films grew coherently strained, with epitaxial relationships of Zn3P2(004)‖GaAs(002) and Zn3P2(202)‖GaAs(111). Partial relaxation of the Zn3P2 lattice was observed for films that were >150 nm in thickness. Van der Pauw and Hall effect measurements indicated that the films were intrinsically p-type, presumably due to the incorporation of phosphorus interstitials. The carrier mobilities in strained films (>40 cm2 V−1 s−1) were comparable to the carrier mobilities that have been reported for bulk Zn3P2 single crystals. The carrier densities and mobilities of holes decreased significantly upon film relaxation, consistent with the evolution of compensating dislocations.

► Zn3P2 epilayers were grown on GaAs(001) by compound-source molecular beam epitaxy.
► The Zn3P2 epilayers were coherently strained up to a critical thickness of 150 nm.
► Strained Zn3P2 films showed hole mobilities comparable to that of single crystals.
► Relaxation in Zn3P2 films caused a large decrease in the hole density and mobility.