Wurtzitic GaN films were grown by reactive crossed-beam pulsed laser deposition at 248 nm (KrF) using a liquid Ga target and a synchronous N2 pulse on atomically flat, initially two domain 2×1 reconstructed Si(001) substrates. The films were (0001) single phase for substrate temperatures between 200 and 700 °C, and also grew in a twinned epitaxial manner with the crystallites oriented parallel to the  and [1¯10] in-plane directions of the Si(001) substrate between 550 and 700 °C. Above 700 °C, no GaN could be detected and only Ga liquid films were produced. The films were subsequently investigated ex situ by x-ray diffraction, reflection high-energy electron diffraction, and photoluminescence. © 1998 American Institute of Physics.