Investigation of Electron Effective Mass in AlGaN/GaN Heterostructures by THz Spectroscopy of Drude Conductivity

Pashnev, Daniil; Korotyeyev, V. V.; Jorudas, Justinas; Urbanowicz, Andrzej; Prystawko, P.; Janonis, Vytautas; Kašalynas, Irmantas

doi:10.1109/ted.2022.3177388

Cited by 9 publications

(5 citation statements)

References 27 publications

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“…In general, the response of the hot carrier detector begins to decrease as the detected frequency approaches the inverse of the momentum relaxation time τ p [8]. The measured Drude conductivity of 2DEG in the AlGaN/GaN structures at room temperature revealed that the carrier relaxation time at low electric field was about 0.3 ps [25]. This suggests that the theoretical cut off frequency for BT diodes could be about 1 THz.…”

Section: Resultsmentioning

confidence: 95%

“…Compared to previously used GaAs-material systems, the selected material has an advantage of a higher electron density, which is useful for a better match between the THz sensor and asymmetric BT antenna impedances [7]. In addition, the short momentum relaxation time of electrons ensures the THz coupling to the 2DEG layer [25,26]. Furthermore, good ohmic contacts to 2DEG in AlGaN/GaN heterostructures can be obtained without the heavy doping of semiconductor layers.…”

Section: Introductionmentioning

confidence: 99%

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Terahertz bow-tie diode based on asymmetrically shaped AlGaN/GaN heterostructures

Jorudas,

Seliuta,

Minkevičius

et al. 2023

physics

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Asymmetrical shaping of AlGaN/GaN heterostructures containing a conductive layer of two-dimensional electron gas (2DEG) was used for the development of bow-tie (BT) diodes for room temperature terahertz (THz) detection. Considering operation of the THz BT diode in the unbiased mode as preferable for practical applications, we investigated the diodes with an obvious asymmetry of IV characteristics, which was found to be more pronounced with the decrease of an apex width, resulting in the sensitive THz detection. A nonuniform heating of carriers in a metalized leaf of the BT diode was attributed as the main mechanism that caused the rectification of THz waves. The responsivity and noise-equivalent power (NEP) at the fundamental antenna frequency of 150 GHz were up to 4 V/W and 2 nW/√Hz, respectively. Such high sensitivity of BT diodes allowed us to measure for the first time the response spectrum of the asymmetric BT antenna demonstrating fundamental and higher order resonances in good agreement with finite-difference time-domain simulation data in a broad spectrum range. The detailed investigation of the lowand high-frequency noise characteristics of AlGaN/GaN BT diodes revealed that only thermal noise needs to be considered for the unbiased operation, the value of which was relatively low due to a high density of 2DEG enabling low resistivity values. Moreover, we observed that the responsivity of BT diode scales with its resistance, revealing that tapering of the diode apex below a few microns could be ineffective in applications which require low NEP values.

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Section: Resultsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Terahertz bow-tie diode based on asymmetrically shaped AlGaN/GaN heterostructures

Jorudas,

Seliuta,

Minkevičius

et al. 2023

physics

Self Cite

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“…For silicon based heterointerface devices however, it is important to note that the lowest energies of the conduction band are not symmetrical, as the constant-energy surfaces are now ellipsoids, rather than the spheres in the case of the III-V materials discussed in (1). Each conduction band minimum can be approximated only by…”

Section: Composite Channel Selectionmentioning

confidence: 99%

“…Composite channel HEMTs attempt to master the governance of electron flow and channel formation within the device by maximizing planar electron concentration at the heterointerfaces and confining the electrons accumulated with the help of a potential energy barrier on either side of the channel. A charge carrier, upon moving from one band to another experiences a change in effective mass dependent on the energies of the bands involved [1,2].…”

Section: Introductionmentioning

confidence: 99%

Composite channel 100 nm InP HEMT with ultrathin barrier for millimetre wave applications

Nandi,

Dubey,

Kumar

et al. 2024

Eng. Res. Express

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This work proposes a new 100 nm InP based InGaAs-InAs-InGaAs composite channel HEMT for millimetre wave applications. The usage of an ultra-thin 2 nm barrier layer, unique composite channel topology and III-V material selection provides superior electron confinement in the channel, enhancing 2DEG concentration and hence, mobility and speed of the proposed device. We achieve a unity current gain frequency (fT) of 248.9 GHz and a maximum oscillation frequency (fMAX) of 523.9 GHz with a current gain of 67.7 dB at 0.1 GHz. Off-state leakage current is in the nanoampere range with minimum noise figure (NFMIN) of only 0.76 dB at 10 GHz. We compare the DC and RF performance and the associated parasitics of different composite channel HEMTs proposed in latest works and mathematically justify why InGaAs-InAs-InGaAs channel HEMTs provide the highest fTand fMAX. InGaAs-InAs-InGaAs channel HEMTs provide 1.4 times better fTand fMAX with only half the NFMINof their InGaAs-InP-InGaAs channel counterparts. A frequency dependent intrinsic FET model is put forward for the proposed HEMT which allows us to model the behavior of the device under varying RF conditions and identify the effect of individual parameters on the entire system.

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“…One of such methods is the THz-TDS system, which has been adapted for such applications [83][84][85][86]. The THz transmission spectra were analyzed considering graphene on the dielectric substrate as the delta-thin conductive layer, which is described by the Drude conductivity model, with fitting parameters of sheet conductivity S σ , scattering time S C τ , and substrate thickness S d [84,85,87]. The transmission spectrum of the graphene sample is shown in Figure 8 by red circles and a fitted curve (black line), which coincide well with experimental points.…”

Section: Electrical Properties Of Graphene After Pmma Removalmentioning

confidence: 99%

Green Removal of DUV-Polarity-Modified PMMA for Wet Transfer of CVD Graphene

et al. 2022

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To fabricate graphene-based high-frequency electronic and optoelectronic devices, there is a high demand for scalable low-contaminated graphene with high mobility. Graphene synthesized via chemical vapor deposition (CVD) on copper foil appears promising for this purpose, but residues from the polymethyl methacrylate (PMMA) layer, used for the wet transfer of CVD graphene, drastically affect the electrical properties of graphene. Here, we demonstrate a scalable and green PMMA removal technique that yields high-mobility graphene on the most common technologically relevant silicon (Si) substrate. As the first step, the polarity of the PMMA was modified under deep-UV irradiation at λ = 254 nm, due to the formation of ketones and aldehydes of higher polarity, which simplifies hydrogen bonding in the step of its dissolution. Modification of PMMA polarity was confirmed by UV and FTIR spectrometry and contact angle measurements. Consecutive dissolution of DUV-exposed PMMA in an environmentally friendly, binary, high-polarity mixture of isopropyl alcohol/water (more commonly alcohol/water) resulted in the rapid and complete removal of DUV-exposed polymers without the degradation of graphene properties, as low-energy exposure does not form free radicals, and thus the released graphene remained intact. The high quality of graphene after PMMA removal was confirmed by SEM, AFM, Raman spectrometry, and by contact and non-contact electrical conductivity measurements. The removal of PMMA from graphene was also performed via other common methods for comparison. The charge carrier mobility in graphene films was found to be up to 6900 cm2/(V·s), demonstrating a high potential of the proposed PMMA removal method in the scalable fabrication of high-performance electronic devices based on CVD graphene.

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Investigation of Electron Effective Mass in AlGaN/GaN Heterostructures by THz Spectroscopy of Drude Conductivity

Cited by 9 publications

References 27 publications

Terahertz bow-tie diode based on asymmetrically shaped AlGaN/GaN heterostructures

Terahertz bow-tie diode based on asymmetrically shaped AlGaN/GaN heterostructures

Composite channel 100 nm InP HEMT with ultrathin barrier for millimetre wave applications

Green Removal of DUV-Polarity-Modified PMMA for Wet Transfer of CVD Graphene

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