Fabrication and characterization of GaN FETs

Binari, S.C.; Kruppa, W.; Dietrich, H. B.; Kelner, G.; Wickenden, A. E.; Freitas, Jaime A.

doi:10.1016/s0038-1101(97)00103-2

Cited by 143 publications

(72 citation statements)

References 15 publications

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“…5. The FET was fabricated with a drainsource spacing of 5 m, a gate width of 150 m and a gate length of 1.5 m. The 200-nm-thick n-GaN active channel layer was grown on top of a 3-m-thick, undoped, highresistivity GaN buffer layer in order to separate the active part of the device from the higher-defect-density material near the sapphire substrate.…”

Section: A Sample and Measurement Characteristicsmentioning

confidence: 99%

“…Current collapse refers to the trapping of charge at defects, after the application of a high drain-source voltage, which results in a significant reduction in the drain current. This effect was recently investigated in a GaN metal-semiconductor field-effect transistor 5 ͑MESFET͒, and was observed only after the device had been subjected to a large drain bias. This is consistent with the view that hot carriers were injected into the high-resistivity ͑HR͒ GaN layer, where they were trapped by deep centers.…”

Section: Introductionmentioning

confidence: 99%

“…Current collapse has been a significant problem in Si metal-oxide-semiconductor FETs, 6 in AlGaAs/GaAs modulation-doped FETs, 7 and more recently in nitride-based AlGaN/GaN heterostructure FETs 8 ͑HFETs͒ and GaN MESFETs. 5,9 An important characteristic of current collapse is that it is reversible with the application of light: the trapped carriers can be photoionized and are thus released from the traps. Under the influence of the built-in electric field that develops in the space-charge region, the photoionized carriers drift rapidly back to the conducting channel.…”

Section: Introductionmentioning

confidence: 99%

“…7 A later probe of AlGaN/GaN devices reported increases in the collapsed drain current due to illumination with near-band gap light and with light near 650 nm, 8 which was associated with an unidentified trap. In studies of current collapse in a GaN MESFET, it was observed 5 that the efficiency of restoring the drain current by light illumination becomes much less effective with increasing wavelength. While current interest is on heterostructure devices because of the high mobility channel formed in these structures, it is also important to understand the nature of the traps in the underlying GaN in order to be able to unravel the contributions to the measured optical response from the various parts of the device structure.…”

Section: Introductionmentioning

confidence: 99%

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Photoionization spectroscopy of traps in GaN metal-semiconductor field-effect transistors

Klein¹,

Binari²,

Freitas³

et al. 2000

Journal of Applied Physics

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Measurements of the spectral and intensity dependences of the optically-induced reversal of current collapse in a GaN metal-semiconductor field-effect transistor ͑MESFET͒ have been compared to calculated results. The model assumes a net transfer of charge from the conducting channel to trapping states in the high-resistivity region of the device. The reversal, a light-induced increase in the trap-limited drain current, results from the photoionization of trapped carriers and their return to the channel under the influence of the built-in electric field associated with the trapped charge distribution. For a MESFET in which two distinct trapping centers have been spectrally resolved, the experimentally measured dependence upon light intensity was fitted using this model. The two traps were found to have very different photoionization cross-sections but comparable concentrations (4ϫ10 11 cm Ϫ2 and 6ϫ10 11 cm Ϫ2 ͒, suggesting that both traps contribute comparably to the observed current collapse. ͓S0021-8979͑00͒00417-5͔

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Section: A Sample and Measurement Characteristicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Photoionization spectroscopy of traps in GaN metal-semiconductor field-effect transistors

Klein¹,

Binari²,

Freitas³

et al. 2000

Journal of Applied Physics

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“…Besides, GaN based devices are plagued by traps that results in performance deteriorating gate-and drain-lag transients and current collapse in the I-V characteristics [10,11]. Trapping effects are dependent upon the applied signal frequency and their effect is more pronounced for frequencies less than the transconductance and output resistance dispersion frequencies [12,13].…”

Section: Ps-2mentioning

confidence: 99%

Thermal and trapping effects in GaN-based MESFETs

Islam

Anwar

Proceedings. IEEE Lester Eastman Conference on High Performance Devices

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RF power performances of GaN-MESFETs are reported using a physics-based model that incorporates dispersion in the output resistance and transconductance due to traps and thermal effects. Calculated I-V characteristics are in excellent agreement with the measured results. Taking thermal effects into account the maximum output power of a 0.3gan x 100arn GaN MESFET is 22dBm at a power gain of 4.2dB at 4GHz. The corresponding quantities are 27dBm and 6.4dB, respectively if a constant channel temperature of 300K is assumed. At elevated temperatures compression in output power, gain and PAE is less in MESFETs with longer gate lengths.

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