Control of epitaxial defects for optimal AlGaN/GaN HEMT performance and reliability

Green, D.S.; Gibb, Shawn R.; Hosse, Brook; Vetury, R.; Grider, David; Smart, J.

doi:10.1016/j.jcrysgro.2004.08.129

Cited by 40 publications

(26 citation statements)

References 9 publications

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“…͑For details of the nucleation layer, see a study about the impact of AlN nucleation conditions on the density and character of threading dislocations emanating from the on SiC substrates. 5 ͒ It is also possible that carbon could be incorporated into the unintentionally doped GaN buffer layer, making it highly resistive, but we have no direct evidence of that fact. Schottky dots of 130 m in diameter and ring-shaped Ohmic contacts surrounding the dots were fabricated on the surface using Ni/Au and Ti/Al/Ni/Au metallizations, respectively.…”

Section: Methodsmentioning

confidence: 89%

Effects of electron-irradiation on electrical properties of AlGaN/GaN Schottky barrier diodes

Fang

Farlow

Claflin

et al. 2009

Journal of Applied Physics

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Effects of 1 MeV electron-irradiation at room temperature on the electrical properties of AlGaN/ GaN heterostructures, including leakage currents, threshold voltages, and electron traps, have been investigated using Schottky barrier diodes ͑SBDs͒ fabricated on the AlGaN. The SBDs, before and after the irradiation with a dose of 5 ϫ 10 15 cm −2 , were characterized by temperature dependent current-voltage and capacitance-voltage measurements and deep level transient spectroscopy. It is found that the irradiation causes ͑i͒ significant increase in leakage currents, dominated by tunneling conduction, at both reverse and low-forward biases; ͑ii͒ a clear negative shift in threshold voltage in the pinch-off region; and ͑iii͒ creation of traps A e ͑ϳ1.1 eV͒ or A 2 ͑1.2 eV͒ and E e ͑0.09 eV͒ in the GaN buffer and AlGaN regions. The irradiation-induced traps can be used to account for the increase in leakage currents and shift in threshold voltage. However, as compared to traps A 2 ͑1.2 eV͒ and E͑0.13 eV͒ induced in thick GaN layers by electron-irradiation, the irradiation-induced traps in the AlGaN/GaN heterostructures show some changes in activation energy and electron capture behavior.

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Section: Methodsmentioning

confidence: 89%

Effects of electron-irradiation on electrical properties of AlGaN/GaN Schottky barrier diodes

Fang

Farlow

Claflin

et al. 2009

Journal of Applied Physics

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“…Many efforts have been made in order to improve the crystalline quality of AlN and to decrease the dislocation density. [2][3][4][5][6][7][8][9] Nevertheless, the current crystalline quality of epitaxial AlN must be improved, particularly for UV LEDs and photodetectors.…”

mentioning

confidence: 99%

Optimization of High-Quality AlN Epitaxially Grown on (0001) Sapphire by Metal-Organic Vapor-Phase Epitaxy

Chen

Mont

et al. 2007

Journal of Elec Materi

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A systematic study is performed to optimize aluminum nitride (AlN) epilayers grown on (0001) sapphire by metal-organic vapor-phase epitaxy. Specifically, the impact of the AlN nucleation conditions on the crystalline quality and surface morphology of AlN epilayers is studied. Atomic force microscopy (AFM) and x-ray diffraction (XRD) results reveal that the nucleation layer plays a critical role in the growth of subsequent layers. The magnitude of the TMAl flow of AlN nucleation layer is found to have a strong effect on the crystalline quality and surface morphology of the high-temperature (HT) AlN epilayer. A simple Al adatom-diffusion-enhancement model is presented to explain the strong dependence of the crystalline quality and surface morphology on TMAl flow. Furthermore, ammonia flow, nucleation temperature, and growth time of the AlN nucleation layer are found to affect the surface morphology and the crystalline quality as well. A trade-off is found between surface morphology and crystalline quality; that is, we do not obtain the best surface morphology and the highest crystalline quality for the same growth parameters. For optimized AlN nucleation layers and HT AlN epilayers, a clear and continuously linear step-flow pattern with saw-tooth shaped terrace edges is found by AFM on AlN epilayers. Triple-axis x-ray rocking curves show a full-width at half-maximum (FWHM) of 11.5 arcsec and 14.5 arcsec for the (002) and (004) reflection, respectively. KOH etching reveals an etch-pit density (EPD) of 2 · 10 7 cm )2 , as deduced from AFM measurements.Aluminum nitride (AlN) has generated much interest due to unique properties such as its very wide and direct bandgap and high thermal conductivity. High-quality AlN epilayers are needed in AlGaN ultraviolet (UV) light-emitting diodes (LEDs), which have great potential for applications such as fluorescence-based biological agent detection, water purification, sterilization, decontamination, nonline-of-sight communications, and thin-film curing. 1 At the same time, deep UV photodetectors need extremely high-quality AlN with low dislocation density for the reduction of the dark current. Many efforts have been made in order to improve the crystalline quality of AlN and to decrease the dislocation density. 2-9 Nevertheless, the current crystalline quality of epitaxial AlN must be improved, particularly for UV LEDs and photodetectors.In this article, we report on the growth of AlN epilayers on (0001) sapphire using the low-temperature (LT) AlN nucleation scheme. 10 The material quality of the AlN epilayers grown on sapphire is determined by atomic force microscopy (AFM) and x-ray diffraction (XRD). A systematic optimi-

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“…It has been reported that device performance is strongly related to dislocations, so the device design mitigates the influence of material imperfections [6]. The increase in dislocation density of AlN films is known to cause electron trapping in metal-insulator-semiconductor field-effect transistor (MISFET) devices [7]. An epitaxial AlN film grown on SiC (0 0 0 1) substrate is expected to reduce the dislocation density and electron trapping.…”

Section: Introductionmentioning

confidence: 99%

Effect of residual H 2 O on epitaxial AlN film growth on 4H-SiC by alternating doses of TMA and NH 3

Perng

Kim

Chang

2014

Applied Surface Science

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Control of epitaxial defects for optimal AlGaN/GaN HEMT performance and reliability

Cited by 40 publications

References 9 publications

Effects of electron-irradiation on electrical properties of AlGaN/GaN Schottky barrier diodes

Effects of electron-irradiation on electrical properties of AlGaN/GaN Schottky barrier diodes

Optimization of High-Quality AlN Epitaxially Grown on (0001) Sapphire by Metal-Organic Vapor-Phase Epitaxy

Effect of residual H 2 O on epitaxial AlN film growth on 4H-SiC by alternating doses of TMA and NH 3

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