Impact of Surface States and Aluminum Mole Fraction on Surface Potential and 2DEG in AlGaN/GaN HEMTs

AbstractThe presence of surface traps is an important phenomenon in AlGaN/GaN HEMT. The electrical and physical properties of these surface traps have been analyzed through the study of 2DEG electron concentration along with the variation of aluminum percentage in the barrier layer of HEMT. This analysis shows that from deep to shallow donors, the percentage change in electron density in 2DEG gets saturated (near 8%) with change in aluminum concentration. The depth of the quantum potential well below the Fermi level is also analyzed and is found to get saturated (near 2%) with aluminum percentage when surface donor states energy changes to deep from shallow. The physics behind this collective effect is also analyzed through band diagram too. The effect of surface donor traps on the surface potential also has been discussed in detail. These surface states are modeled as donor states. Deep donor (EC − ED = 1.4 eV) to shallow donor (EC − ED = 0.2 eV) surface traps are thoroughly studied for the donor concentration of 1011 to 1016 cm−2. This study involves an aluminum concentration variation from 5 to 50%. This paper for the first time presents the comprehensive TCAD study of surface donor and analysis of electron concentration in the channel and 2DEG formation at AlGaN–GaN interface.

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Positron Lifetime at Deep Donors of Radiation Origin in Proton - Irradiated FZ-Silicon Single Crystals

Materials Science Forum ◽

10.4028/www.scientific.net/msf.733.224 ◽

2012 ◽

Vol 733 ◽

pp. 224-227 ◽

Cited By ~ 1

Author(s):

Nikolai Yu. Arutynov ◽

Mohamed Elsayed ◽

Reinhard Krause-Rehberg ◽

Valentin V. Emtsev ◽

Gagik A. Oganesyan ◽

...

Keyword(s):

Activation Energy ◽

Room Temperature ◽

Positron Lifetime ◽

Shallow Donor ◽

Electrical Measurements ◽

Positron Annihilation Lifetime ◽

First Order ◽

Deep Donor ◽

Donor States ◽

Mev Protons

The recovery of shallow donor states of the atoms of phosphorus in n-FZ-Si:P material irradiated at the room temperature with 15 MeV protons was studied in the course of isochronal annealing. This process was investigated by the positron annihilation lifetime (PAL) spectroscopy and by low-temperature electrical measurements. The positron traps of a vacancy type manifesting themselves as deep donors have been revealed. These defects begin to anneal at ~ 593 K– 613 K; roughly estimated activation energy of the process is Ea ≈ 0.59 eV under the first order of reaction. The results suggest the involvement, at least, of one vacancy and the impurity atom of phosphorus in the microstructure of the deep donor.

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2D weak anti-localization in thin films of the topological semimetal Pd$$_{3}$$Bi$$_{2}$$S$$_{2}$$

Scientific Reports ◽

10.1038/s41598-021-91930-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Shama ◽

R. K. Gopal ◽

Goutam Sheet ◽

Yogesh Singh

Keyword(s):

Thin Films ◽

Phonon Scattering ◽

Surface States ◽

Relaxation Mechanism ◽

Transport Studies ◽

Bulk Carriers ◽

Topological Semimetal ◽

Topological Surface ◽

First Time ◽

Electron Phonon Scattering

AbstractPd$$_{3}$$ 3 Bi$$_{2}$$ 2 S$$_{2}$$ 2 (PBS) is a recently proposed topological semimetal candidate. However, evidence for topological surface states have not yet been revealed in transport measurements due to the large mobility of bulk carriers. We report the growth and magneto-transport studies of PBS thin films where the mobility of the bulk carriers is reduced by two orders of magnitude, revealing for the first time, contributions from the 2-dimensional (2D) topological surface states in the observation of the 2D weak anti-localization (WAL) effect in magnetic field and angle dependent conductivity measurements. The magnetotransport data is analysed within the 2D Hikami-Larkin-Nagaoka (HLN) theory. The analysis suggests that multiple conduction channels contribute to the transport. It is also found that the temperature dependence of the dephasing length can’t be explained only by electron-electron scattering and that electron-phonon scattering also contributes to the phase relaxation mechanism in PBS films.

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