Raman and Brillouin scattering spectroscopy studies of atomic layer-deposited ZrO(2) and HfO(2) thin films.

Atomic layer-deposited ZrO(2) (zirconia) and HfO(2) (hafnia) films with various thicknesses, ranging from 112 to 660 nm, have been studied by Raman scattering spectroscopy. Spectral analysis of the excellent quality Raman data obtained by using freestanding edges of the films has unambiguously demonstrated that a metastable tetragonal t-ZrO(2) is coexisting with the stable monoclinic phase in zirconia films. Even though the Raman spectrum signal-to-noise ratio was high, only the monoclinic phase was positively identified from the observed spectral patterns of hafnia films. X-ray diffraction patterns are used to define the structure of metastable phases. Complementary Brillouin light scattering measurements of the freestanding edges are also employed in constraining elastic properties of the 405 nm HfO(2) thin film.

High performance laser diode bars with aluminum-free active regions.

We present operating and lifetest data on 795 and 808 nm bars with aluminum-free active regions. Conductively cooled bars operate reliably at CW power outputs of 40 W, and have high efficiency, low beam divergence, and narrow spectra. Record CW powers of 115 W CW are demonstrated at 795 nm for 30% fill-factor bars mounted on microchannel coolers. We also review QCW performance and lifetime for higher fill-factor bars processed on identical epitaxial material.