Photoelastic properties of zinc-blende AlxGa1−xN in the UV: Picosecond ultrasonic studies

Abstract

Picosecond ultrasonics was used to study the photoelastic properties of zinc-blende (cubic) c-Al x Ga 1−x N with x around 0.5. The velocities for longitudinal sound in the alloys were measured using ultrafast UV pump-probe experiments with (AlGa)N membranes. Strong Brillouin oscillations were observed in (AlGa)N films attached to GaAs substrates. These oscillations are due to the dynamical interference of the probe beams reflected from the sample surface and interfaces and a picosecond-duration strain pulse propagating in the alloy layer. Optical and elasto-optical parameters including the complex refractive index and the fundamental band gap of the cubic nitride alloys are determined and compared with the values obtained by ellipsometry.

The effective light‐harvesting performance of graded compositional Al x Ga 1−x N nano‐cone arrays photocathode for ultraviolet detector—A numerical investigation and simulation

“…The bottom‐up changes of component x are x = 1, x = 0.66, x = 0.49, x = 0.42, x = 0.19, x = 0.151, x = 0.087, and x = 0. The material refractive index and extinction coefficient with Al composition x = 0, x = 0.19, Al composition x = 0.087, x = 0.151, Al composition x = 0.42, x = 0.49, x = 0.66 are respectively from the experimental data of Antoine‐Vincenta, Yu, Whale . The specific optical refractive index is shown in Figure B.…”

Enhanced Collection Efficiency of Photoelectrons of Negative Electron Affinity AlGaN Heterojunction Nanorod Array Photocathodes

“…6. 37,38 The absorptivity calculated by COMSOL is used to calculate the carrier generation function in Eq. 1.…”

Shear wave generation by mode conversion in picosecond ultrasonics: Impact of grain orientation and material properties

“…The longitudinal wave is frequently utilized because it has the largest amplitude 19 . Although usually much weaker in amplitude, the excitation of shear waves extends the characterization from only longitudinal direction to transverse directions and thus expands the range of measurable physical properties from experiments 25‐29 . For example, these additional properties could be off‐diagonal elements of elastic tensor 14 or grain orientations 30 .…”

“…19 Although usually much | 2789 WANG ANd KHAFIZOV weaker in amplitude, the excitation of shear waves extends the characterization from only longitudinal direction to transverse directions and thus expands the range of measurable physical properties from experiments. [25][26][27][28][29] For example, these additional properties could be off-diagonal elements of elastic tensor 14 or grain orientations. 30 Moreover, the transverse nature of shear modes is inherently suitable to study layered structure and examine bonding strengths.…”