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

Tetragonal zinc phosphide (alpha-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(1 (1) under bar1). 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 cm(2) 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. (C) 2012 Elsevier B.V. All rights reserved.