Growth and optical characterization of aluminum nitride thin films deposited on silicon by radio-frequency sputtering

Highly textured hexagonal aluminum nitride (AlN) thin films were deposited on silicon substrates by radio-frequency magnetron sputtering at a substrate temperature below 400 degrees C and annealed in the temperature range of 400-450 degrees C by rapid thermal annealing. The optical and the electro-optical properties have been investigated using the prism-coupling technique. Both ordinary and extraordinary refractive indices (n(o) = 2.0058 and n(e) = 2.0374 at 632.8 nm) were respectively determined from the transverse electric and the transverse magnetic mode excitations. Furthermore, refractive index profiles analysis by using an improved inverse Wentzel-Kramer-Brillouin method reveals a step-like behavior of AlN thin films. The optical losses have been evaluated to be around 7 dB cm(-1). The electro-optic coefficient r(13) of 0.98 pm/V has been measured from the variation of the shift of guided-modes spectrum as a function of the applied electric field in the experiment. (C) 1999 American Institute of Physics. [S0003-6951(99)03709-2].