Advanced Terahertz Frequency-Domain Ellipsometry Instrumentation for In Situ and Ex Situ Applications

P Kühne, N Armakavicius, V Stanishev… - IEEE Transactions …, 2018 - ieeexplore.ieee.org
We present a terahertz (THz) frequency-domain spectroscopic ellipsometer design that
suppresses formation of standing waves by use of stealth technology approaches. The …

[HTML][HTML] Mg-doping and free-hole properties of hot-wall MOCVD GaN

A Papamichail, A Kakanakova-Georgieva… - Journal of Applied …, 2022 - pubs.aip.org
The hot-wall metal-organic chemical vapor deposition (MOCVD), previously shown to
enable superior III-nitride material quality and high performance devices, has been explored …

[HTML][HTML] Tuning composition in graded AlGaN channel HEMTs toward improved linearity for low-noise radio-frequency amplifiers

A Papamichail, AR Persson, S Richter, P Kühne… - Applied Physics …, 2023 - pubs.aip.org
Compositionally graded channel AlGaN/GaN high electron mobility transistors (HEMTs) offer
a promising route to improve device linearity, which is necessary for low-noise radio …

High-frequency conductivity and temperature dependence of electron effective mass in AlGaN/GaN heterostructures

VV Korotyeyev, VA Kochelap, VV Kaliuzhnyi… - Applied Physics …, 2022 - pubs.aip.org
We present calculations of frequency and wavevector dispersion of conductivity of two-
dimensional electrons confined in AlGaN/GaN heterostructures at the arbitrary level of the …

Beatings of ratchet current magneto-oscillations in GaN-based grating gate structures: Manifestation of spin-orbit band splitting

P Sai, SO Potashin, M Szoła, D Yavorskiy, G Cywiński… - Physical Review B, 2021 - APS
We report on the study of the magnetic ratchet effect in AlGaN/GaN heterostructures
superimposed with a lateral superlattice formed by a dual-grating gate structure. We …

[HTML][HTML] Electron effective mass in GaN revisited: New insights from terahertz and mid-infrared optical Hall effect

N Armakavicius, S Knight, P Kühne, V Stanishev… - APL Materials, 2024 - pubs.aip.org
Electron effective mass is a fundamental material parameter defining the free charge carrier
transport properties, but it is very challenging to be experimentally determined at high …

[HTML][HTML] Optical phonon modes, static and high-frequency dielectric constants, and effective electron mass parameter in cubic In2O3

M Stokey, R Korlacki, S Knight, A Ruder… - Journal of Applied …, 2021 - pubs.aip.org
A complete set of all optical phonon modes predicted by symmetry for bixbyite structure
indium oxide is reported here from a combination of far-infrared and infrared spectroscopic …

[HTML][HTML] Impact of Al profile in high-Al content AlGaN/GaN HEMTs on the 2DEG properties

A Papamichail, AR Persson, S Richter… - Applied Physics …, 2024 - pubs.aip.org
Ultra-thin high-Al content barrier layers can enable improved gate control and high-
frequency operation of AlGaN/GaN high electron mobility transistors (HEMTs) but the …

Investigation of electron effective mass in AlGaN/GaN heterostructures by THz spectroscopy of drude conductivity

D Pashnev, VV Korotyeyev, J Jorudas… - … on Electron Devices, 2022 - ieeexplore.ieee.org
Terahertz time domain spectroscopy (TDS) of the two-dimensional (2-D) electrons in various
commercial AlGaN/GaN heterostructures was performed in the frequency range of 0.1–2.0 …

Is happiness infectious?

J Knight, R Gunatilaka - Scottish Journal of Political Economy, 2017 - Wiley Online Library
The paper uses an appropriate survey from rural China to answer the question: is happiness
infectious, ie does the happiness of an individual depend positively on the happiness of his …