Properties of GaN thin films prepared by laser induced molecular beam epitaxy

Kurzfassung

We achieve high quality epitaxial GaN film growth on sapphire (0001) and 6H-SiC (0001) substrates by laser induced molecular beam epitaxy (LIMBE). Pure metal targets were ablated with a picosecond Nd:YAG laser in a nitrogen atmospere of 5E-02mbar. The films were grown at substrate temperatures between 700 and 800°C. Composition, structure and optical properties of the nitride films were chara<cterized with EDX, TEM, XRD, x-ray rocking curve measurements, AFM, SEM and PL spectroscopy. The films are smooth, stoichiometric, (0001) oriented and consist purely of the wurtzite phase. They show a x-ray rocking curve FWHM of 9 arcmin and a strong excitonic emission with a FWHM of 6.4meV in the PL spectrum at 4.3 K. Recent results of DLTS investigations on our GaN films revealed a residual carrier concentration of <1.E+17cm^-3.