| 1. |
- Knight, Sean Robert, et al.
(författare)
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Room temperature two-dimensional electron gas scattering time, effective mass, and mobility parameters in AlxGa1−xN/GaN heterostructures (0.07 ≤ x ≤ 0.42)
- 2023
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Ingår i: Journal of Applied Physics. - : American Institute of Physics Inc.. - 0021-8979 .- 1089-7550. ; 134:18
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Tidskriftsartikel (refereegranskat)abstract
- Al xGa 1−xN/GaN high-electron-mobility transistor (HEMT) structures are key components in electronic devices operating at gigahertz or higher frequencies. In order to optimize such HEMT structures, understanding their electronic response at high frequencies and room temperature is required. Here, we present a study of the room temperature free charge carrier properties of the two-dimensional electron gas (2DEG) in HEMT structures with varying Al content in the Al xGa 1−xN barrier layers between x=0.07 and x=0.42. We discuss and compare 2DEG sheet density, mobility, effective mass, sheet resistance, and scattering times, which are determined by theoretical calculations, contactless Hall effect, capacitance-voltage, Eddy current, and cavity-enhanced terahertz optical Hall effect (THz-OHE) measurements using a low-field permanent magnet (0.6 T). From our THz-OHE results, we observe that the measured mobility reduction from x=0.13 to x=0.42 is driven by the decrease in 2DEG scattering time, and not the change in effective mass. For x<0.42, the 2DEG effective mass is found to be larger than for electrons in bulk GaN, which in turn, contributes to a decrease in the principally achievable mobility. From our theoretical calculations, we find that values close to 0.3 m0 can be explained by the combined effects of conduction band nonparabolicity, polarons, and hybridization of the electron wavefunction through penetration into the barrier layer.
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| 3. |
- Rindert, Viktor, et al.
(författare)
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THz Spectroscopic Electron Paramagnetic Resonance of the Fe3+ Defect in GaN
- 2023
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Ingår i: 2023 48TH INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER, AND TERAHERTZ WAVES, IRMMW-THZ. - : IEEE. - 2162-2035 .- 2162-2027. - 9798350336603 - 9798350336610
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Konferensbidrag (refereegranskat)abstract
- We present a recently developed method for electron paramagnetic resonance (EPR) measurements in the THz spectral range. The method is based on spectroscopic ellipsometry and thus requires no cavity, unlike conventional EPR. This permits us to scan the frequency parameters in addition to the magnetic field parameters. To showcase this, both frequency and magnetic field scans are performed on Fe-doped GaN, and the results are compared to previous work that used conventional EPR to study the same defect.
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