Properties and application of ultrasonic Lamb waves in CdxHg₁₋xTe plates

Group and phase velocities of the lowest orders of Lamb waves in , directions for (100) Cd₀.₂Hg₀.₈Te plates are calculated. Frequency dispersion of a₀ and s₀ Lamb modes velocities were measured on (111)-plates in the range of frequencies from 0.2 to 10 MHz. The frequency dependencies of relative efficiency of the Lamb modes excitation using two geometrical versions: symmetrical - with two piezoelectric transducers, and antisymmetrical - with one piezoelectric transducer, have been studied. Possible applications of studied waves including ultrasonic treatment of semiconductors have been discussed

Sub-THz nonresonant detection in AlGaN/GaN heterojunction FETs

Un-cooled AlGaN/GaN-based heterojunction field-effect transistors (HFET) designed on sapphire (0001) substrates were considered as 140 GHz direct detection detectors without any specially attached antennas. The noise equivalent power (NEP) of these detectors was ~ 10⁻¹⁰ W/Hz¹/² in the observed radiation frequency range at ambient temperatures. It has been shown that the ultimate value for the AlGaN/GaN HFET detectors (in 0.25-μm technology) can reach NEPopt ≈ 6•10⁻¹² W/Hz¹/² , and it is 3-fold lower than that for Si MOSFET (in 0.35-μm technology)

Anisotropy of ultrasonic waves propagation velocities in CdHgTe/CdTe

The complete set of elastic moduli of Cd₀.₂Hg₀.₈Te was obtained. Taking into account elastic moduli found for Cd₀.₂Hg₀.₈Te and appropriate literary data for CdTe the anisotropy of velocities of volume and Rayleigh waves propagating on (100) and (110) boundaries was calculated. Finally, peculiarities of the anisotropy of SAW propagating velocities for each of components of layered structures CdHgTe/CdTe and for the heteroepitaxial structure as a whole were analysed