Optical and electrical properties of Al1-xInxN films grown by plasma source molecular-beam epitaxy

Epitaxial Al1-xInxN thin films with 0 less than or equal tox less than or equal to1 have been grown by plasma source molecular beam epitaxy on sapphire (0001) substrates at a low temperature of 375 degreesC. Both reflection high-energy electron diffraction and x-ray diffraction measurements confirm the c-plane growth with the following epitaxial relations: nitride [0001] parallel to sapphire [0001] and nitride [01 (1) over bar(1) over bar0] parallel to sapphire [2 (1) over bar0]. However, the degree of crystalline mosaicity and the compositional fluctuation increase with increasing x. The observed direct energy band gap, determined using optical transmission and reflection measurements show relatively less bowing compared to some earlier studies. Electrical resistivity and Hall effect measurements show n-type electrical conductivity in these alloys with carrier concentrations n greater than or equal to 10(19) cm(-3) for In-rich alloys and n less than or equal to 10(10) cm(-3) for Al-rich alloys. (C) 2001 American Institute of Physics.