Nonpolar a-plane GaN film on Si(100) produced using a specially designed lattice-matched buffer: A fresh approach to eliminate the polarization effect

Using pulsed laser deposition, nonpolar a-plane GaN thin films were grown on Si(100) substrates coated with a nonpolar MnS(100) plane buffer layer. The film showed an epitaxial relationship of GaN(112¯0)∥MnS(100)∥Si(100) with an in-plane alignment of GaN[1¯100]∥MnS[010]∥Si[010]. The high-resolution cross-sectional transmission electron microscopy image of the GaN∕MnS interface showed an abrupt atomic interface. A strong band-edge emission from the GaN film was observed at 364.3nm (=3.4eV) in cathodoluminescence measurements at 30K. This result in controlling the growth plane provides GaN films free of polarization effects in the direction of film growth, which favor the integration of optoelectronic devices combined with silicon.