Temperature Distribution Measurement in AlGaN/GaN High-Electron-Mobility Transistors by Micro-Raman Scattering Spectroscopy

Ohno, Yutaka; Akita, M.; Kishimoto, Shigeru; Maezawa, Koichi; Mizutani, Takashi

doi:10.1143/jjap.41.l452

Cited by 22 publications

(19 citation statements)

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“…Even though much progress has been achieved [3][4][5], there are still some issues, which should be addressed such as current collapse [6][7][8], temperature increase due to a large thermal resistance [9], and understandings of transport properties at high temperature [10]. Among these issues, the current collapse is very important because microwave output power is limited by this current collapse.…”

Section: Introductionmentioning

confidence: 99%

Current Collapse in AlGaN/GaN HEMTs Investigated by Electrical and Optical Characterizations

Mizutani

Ohno

Akita

et al. 2002

phys. stat. sol. (a)

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Drain current collapse in AlGaN/GaN HEMTs has been studied in detail. Applying negative gate bias stress to the device caused a serious current collapse. Spatially resolved light illumination on the device combined with the measurement of series source and drain resistances revealed that the collapse was caused by the electrons trapped at the surface states between the gate and drain electrodes. Passivation of the device surface with Si3N4 film eliminated the current collapse.

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Section: Introductionmentioning

confidence: 99%

Current Collapse in AlGaN/GaN HEMTs Investigated by Electrical and Optical Characterizations

Mizutani

Ohno

Akita

et al. 2002

phys. stat. sol. (a)

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“…At higher temperatures, on the other hand, the deeper interface states can produce larger amounts of charges, particularly under bias conditions for depletion. Since high-power operation significantly increases the channel temperature in the GaN-based transistors [6][7][8], such interface charges may impede …”

mentioning

confidence: 99%

Temperature-Dependent Interface-State Response in an Al₂O₃/n-GaN Structure

Ooyama

Kato

Miczek

et al. 2008

jjap

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With a combination of the static capacitance-voltage (C-V) and the capacitance transient (C-t) methods, the interface-state response in an Al 2 O 3 /n-GaN structure was investigated at temperatures ranging from 23 to 300 o C. We observed pronounced degradation of the static C-V curves measured at high temperatures, arising from the enhancement of charging/discharging rates of interface states at deeper energies within the bandgap of GaN. Faster responses with larger magnitudes also appeared in the time-dependent capacitance at high temperatures. From a simple analysis of the C-t results, we estimated the capture cross section of the states to be on the order of 10 -19 cm 2 .KEYWORDS: GaN, MIS, interface state, C-V, C-t, high temperature, capture cross section *E-mail address: hashi@rciqe.hokudai.ac.jpAn insulated-gate structure is very attractive for GaN-based high-efficiency power switching devices and high-power transistors operating at high frequency [1][2][3]. For realization of well-controlled and reliable insulated-gate structure, it is necessary to achieve an insulator-semiconductor (I-S) interface with a low density of electronic states [1,4,5]. To characterize the properties of interface states, a static capacitance-voltage (C-V) method is generally used.In the case of GaN I-S structures, however, it is difficult, from the room-temperature (RT) C-V method, to gain information on the interface states located near midgap or deeper, because the wide-gap nature of GaN makes the time constant for carrier emission from deeper states extremely large at RT. In this case, as schematically shown in Fig. 1, the charging state remains almost unchanged while the gate bias is swept in the C-V measurements even if the interface states have high densities. Thus, it should be pointed out that the RT C-V method only provides the response of the states with a limited energy range near the conduction band minimum or the valence band maximum. At higher temperatures, on the other hand, the deeper interface states can produce larger amounts of charges, particularly under bias conditions for depletion. Since high-power operation significantly increases the channel temperature in the GaN-based transistors [6][7][8], such interface charges may impede

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“…, and B ¼ 1.04 AE 0.01 for the present HEMT epitaxial wafer [4]. The temperature error is less than 10 K at 300 K.…”

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confidence: 62%

“…Thermal management is an important issue for realizing a higher output power level. In order to achieve good thermal management in AlGaN/GaN HEMTs, it is important to understand the thermal conduction in the devices under operation, based on direct measurements of the local temperature distribution [3,4].In this work, we investigated the temperature distribution in AlGaN/GaN HEMTs on a sapphire substrate using micro-Raman scattering spectroscopy. The power dependence of the channel temperature and thermal resistance of the devices are also discussed, comparing them with simulation results.…”

mentioning

confidence: 99%

Temperature Distributions in AlGaN/GaN HEMTs Measured by Micro‐Raman Scattering Spectroscopy

Ohno

Akita

Kishimoto

et al. 2002

phys. stat. sol. (c)

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.FsTemperature distributions in AlGaN/GaN high-electron-mobility transistors under bias voltage have been measured by micro-Raman scattering spectroscopy. The temperature was estimated from the Raman shift of E 2 phonons of GaN. The spatial and temperature resolutions were 1 mm and 10 K, respectively. When the power dissipation was 248 mW at a drain voltage of 40 V, a peak temperature of 428 K was observed at the gate edge on the drain side at the center of the channel. The position of the highest temperature corresponds to the high-field region at the gate edge. Peak temperature increased superlinearly with the power dissipation, which is probably due to the temperature-dependent thermal conductivity of the materials.Introduction AlGaN/GaN high-electron-mobility transistors (HEMTs) receive much attention for high-frequency and high-power applications because of their advantages, such as the high breakdown field, high drift velocity, and high electron density [1,2]. Thermal management is an important issue for realizing a higher output power level. In order to achieve good thermal management in AlGaN/GaN HEMTs, it is important to understand the thermal conduction in the devices under operation, based on direct measurements of the local temperature distribution [3,4].In this work, we investigated the temperature distribution in AlGaN/GaN HEMTs on a sapphire substrate using micro-Raman scattering spectroscopy. The power dependence of the channel temperature and thermal resistance of the devices are also discussed, comparing them with simulation results.

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Temperature Distribution Measurement in AlGaN/GaN High-Electron-Mobility Transistors by Micro-Raman Scattering Spectroscopy

Cited by 22 publications

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Current Collapse in AlGaN/GaN HEMTs Investigated by Electrical and Optical Characterizations

Current Collapse in AlGaN/GaN HEMTs Investigated by Electrical and Optical Characterizations

Temperature-Dependent Interface-State Response in an Al₂O₃/n-GaN Structure

Temperature Distributions in AlGaN/GaN HEMTs Measured by Micro‐Raman Scattering Spectroscopy

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Temperature Distribution Measurement in AlGaN/GaN High-Electron-Mobility Transistors by Micro-Raman Scattering Spectroscopy

Cited by 22 publications

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Current Collapse in AlGaN/GaN HEMTs Investigated by Electrical and Optical Characterizations

Current Collapse in AlGaN/GaN HEMTs Investigated by Electrical and Optical Characterizations

Temperature-Dependent Interface-State Response in an Al2O3/n-GaN Structure

Temperature Distributions in AlGaN/GaN HEMTs Measured by Micro‐Raman Scattering Spectroscopy

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Temperature-Dependent Interface-State Response in an Al₂O₃/n-GaN Structure