Self-Heating of Annealed Ti/Al/Ni/Au Contacts to Two-Dimensional Electron Gas in AlGaN/GaN Heterostructures

Šermukšnis, E.; Jorudas, Justinas; Šimukovič, A.; Kovalevskij, Vitalij; Kašalynas, Irmantas

doi:10.3390/app122111079

Cited by 5 publications

(6 citation statements)

References 59 publications

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“…2. Here more pronounced carrier heating in the shaped sub-contact area in comparison to the 2DEG channel can be identified [12,27]. These BT diodes demonstrated a sensitive THz detection in the unbiased regime, thus, only data for those will be discussed further.…”

Section: Resultsmentioning

confidence: 97%

“…Furthermore, good ohmic contacts to 2DEG in AlGaN/GaN heterostructures can be obtained without the heavy doping of semiconductor layers. This simplifies the interpretation of THz signals caused by carrier heating in the asymmetrically necked contact and semiconductor materials if one takes into account self-heating effects of both ohmic contacts and 2DEG layer, observed even under short-duration (only 100 ns) and low-duty-cycle (only 10 -5 ) pulsed electric fields [27].…”

Section: Introductionmentioning

confidence: 95%

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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: 97%

Section: Introductionmentioning

confidence: 95%

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

Jorudas,

Seliuta,

Minkevičius

et al. 2023

physics

Self Cite

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“…In particular, the excess noise temperature strongly decreases as L increases for thick-barrier sample A1. Such a strongly decreasing dependence on L is an indication that the noise is mainly a result of the contact resistance [41]. However, in the case of thin-barrier samples, △T n does not noticeably decrease on L. Moreover, the dependence shows the opposite trend in some thin-barrier samples at higher currents (Figure 6).…”

Section: Discussionmentioning

confidence: 95%

“…The noise data for different-length (L) channels of thick-barrier heterostructure (sample A1, ∼40 nm barrier thickness) are shown in Figure 5. The different-length channels are compared in the noise-current representation, which allows us to evaluate the effect of contact resistance [41]. In particular, the excess noise temperature strongly decreases as L increases for thick-barrier sample A1.…”

Section: Discussionmentioning

confidence: 99%

Hot-Electron Microwave Noise and Energy Relaxation in (Be)MgZnO/ZnO Heterostructures

Šermukšnis,

Šimukovič,

Avrutin

et al. 2024

Crystals

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Pulsed hot-electron microwave noise measurements of the (Be)MgZnO/ZnO heterostructures are presented in this work. The heterostructures of different barrier thicknesses and different bulk electron densities in ZnO layer are compared. Capacitance–voltage (C–V) measurements reveal the decrease in the two-dimensional electron gas (2DEG) peak in electron density profile at the Zn-polar BeMgZnO/ZnO interface as the BeMgZnO barrier layer thickness decreases. For thin-barrier heterostructures, the peak disappears and only the bulk electron density is resolved in C–V measurements. The excess noise temperature at ∼10 GHz in thick-barrier heterostructures is noticeably higher (∼10 times) compared to thin-barrier heterostructures, which is attributed to the strong noise source in the contacts of the former. In the case of thin-barrier heterostructures, at electric fields above ∼10 kV/cm and electron density ≳1×1017cm−3, strong noise source is resolved, which was also observed earlier in the Ga-doped ZnO films due to the formation of self-supporting high-field domains. However, for the low electron densities (≲6 ×1016 cm−3), the aforementioned noise source is not observed, which suggests the importance of a deep ZnO/GaN interface with 2DEG for power dissipation. The hot-electron temperature dependence on the dissipated power of those low-electron-density heterostructures is similar to that of O-polar ZnO/MgZnO. The estimated electron energy relaxation time in ZnO/MgZnO is ∼0.45 ps ± 0.05 ps at dissipated electrical power per electron of ∼0.1 nW/el and approaches ∼0.1 ps as the dissipated power is increased above ∼10 nW/el.

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“…Owing to their high frequency and power handling potentialities, AlGaN/GaN high-electron-mobility transistors (HEMTs) are expected to play substantial roles in future satellite and information technologies [ 1 , 2 , 3 , 4 ]. The majority of the power of such devices is dissipated over relatively small areas of about 0.5–1 μm around the gate contact, resulting in local Joule self-heating [ 5 , 6 , 7 , 8 , 9 , 10 ]. The performance of a device is usually influenced by self-heating; this can be identified by evaluating the thermal impedance on various epi-structures and substrates (Si, SiC, and sapphire) [ 11 , 12 , 13 ].…”

Section: Introductionmentioning

confidence: 99%

Explicit Thermal Resistance Model of Self-Heating Effects of AlGaN/GaN HEMTs with Linear and Non-Linear Thermal Conductivity

et al. 2022

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We presented an explicit empirical model of the thermal resistance of AlGaN/GaN high-electron-mobility transistors on three distinct substrates, including sapphire, SiC, and Si. This model considered both a linear and non-linear thermal resistance model of AlGaN/GaN HEMT, the thickness of the host substrate layers, and the gate length and width. The non-linear nature of channel temperature—visible at the high-power dissipation stage—along with linear dependency, was constructed within a single equation. Comparisons with the channel temperature measurement procedure (DC) and charge-control-based device modeling were performed to verify the model’s validity, and the results were in favorable agreement with the observed model data, with only a 1.5% error rate compared to the measurement data. An agile expression for the channel temperature is also important for designing power devices and monolithic microwave integrated circuits. The suggested approach provides several techniques for investigation that could otherwise be impractical or unattainable when utilizing time-consuming numerical simulations.

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Self-Heating of Annealed Ti/Al/Ni/Au Contacts to Two-Dimensional Electron Gas in AlGaN/GaN Heterostructures

Cited by 5 publications

References 59 publications

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

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

Hot-Electron Microwave Noise and Energy Relaxation in (Be)MgZnO/ZnO Heterostructures

Explicit Thermal Resistance Model of Self-Heating Effects of AlGaN/GaN HEMTs with Linear and Non-Linear Thermal Conductivity

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