Effect of Different Carbon Doping Techniques on the Dynamic Properties of GaN-on-Si Buffers

Yacoub, Hady; Mauder, C.; Eickelkamp, M.; Fahle, Dirk; Heuken, M.; Kalisch, H.; Vescan, A.

doi:10.1109/ted.2017.2647841

Cited by 33 publications

(16 citation statements)

References 23 publications

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“…In experiments D and E the Fedoped layer was grown as usual, but the first 400 nm of the undoped GaN were grown respectively at an intermediate and at a colder temperature. In these cases the C-concentration was below 1 Â 10 19 and above 1 Â 10 20 atoms cm À3 , respectively. The remaining 300 nm of undoped GaN were grown on top, followed by the barrier and cap layers.…”

Section: Resultsmentioning

confidence: 88%

“…Carbon (C) has the advantage to be easily controllable in the epitaxial growth. GaN layers can be grown with high C concentration (high 1 × 10 19 cm −3 range) by means of intrinsic or extrinsic doping, and then abruptly turn to unintentionally doped GaN with C concentration below 1 × 10 16 cm −3 . When its concentration is below 1 × 10 19 cm −3 , the C atoms occupy the site of nitrogen atoms (C N ) in the GaN crystal structure and behave as deep acceptor, at higher concentrations C will occupy the Ga‐sites (C Ga ) and start to behave as a donor .…”

Section: Introductionmentioning

confidence: 99%

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Suppression of Iron Memory Effect in GaN Epitaxial Layers

Benkhelifa

Kirste

Manz

et al. 2017

Physica Status Solidi (b)

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AlGaN/GaN High Electron Mobility Transistors (HEMTs) require a semi‐insulating buffer to compensate a high background donor concentration and to prevent parasitic effects, such as parallel conduction. Iron and carbon are typical impurities used for such purpose, since they can behave as deep acceptors in GaN layers. The former (Fe) brings as drawback a well‐known memory effect which consists in the segregation of Fe atoms through the GaN layers, requiring thick undoped layers to keep the two‐dimensional electron gas (2DEG) away from such electron traps. The latter (C), although easier to incorporate in the GaN layers and free of any memory effect, could cause current collapse. In this study we investigate the effect of differently strained epitaxial layers on Fe‐segregation. HEMT structures were grown on sapphire substrates by MOCVD. By growing the Fe‐doped layers under unusual growth conditions (low temperature, or as AlGaN), or by adding an interlayer (AlN, 5× AlN/GaN, or C‐doped GaN) between the doped and undoped epitaxial layers, we have succeeded in limiting the Fe segregation within 200 nm of undoped GaN layer instead of the typically required 800 nm, as proven by SIMS. While the morphology and the crystal quality of the HEMT structures have been affected to a very low extent, the electrical characteristics have benefitted from such interlayers. Higher carrier mobility and lower sheet resistance distinguish such epitaxial structures. Further benefits are expected by the device performance such as reduced soft‐subthreshold behavior (soft‐breakdown) and dispersion effects.

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Section: Resultsmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Suppression of Iron Memory Effect in GaN Epitaxial Layers

Benkhelifa

Kirste

Manz

et al. 2017

Physica Status Solidi (b)

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“…In these measurements, the silicon substrate bias was ramped from 0 to −200 V and back with a sweep rate of 10 Vs. No noticeable difference in the dynamic properties of both GaN buffers was observed indicating that the MBE‐based nucleation has little or no effect on the subsequent GaN buffer quality. The conductance hysteresis seen in both samples can be attributed to carbon traps in the GaN buffer …”

Section: Resultsmentioning

confidence: 93%

Impact of AlN/Si Nucleation Layers Grown Either by NH₃‐MBE or MOCVD on the Properties of AlGaN/GaN HFETs

Yacoub¹,

Zweipfennig²,

Kalisch³

et al. 2018

Physica Status Solidi (a)

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Epitaxial growth of group III nitrides on silicon substrates is challenging as large lattice and thermal expansion coefficient mismatches have to be accounted for. It is generally accepted that AlN is the best nucleation layer for GaN‐on‐Si growth. However, some open questions remain about this AlN nucleation layer. In this study, it is investigated how the choice of deposition method of the AlN nucleation layer affects the material and electrical properties of a full HFET structure. First, electrical characterization is performed on thin AlN layers deposited on two inch p‐type silicon substrates grown by NH3‐MBE. CV characteristics indicate that electron injection from an inversion‐like layer at the AlN/Si‐interface is suppressed. Based on previous studies, this leads to the expectation that choosing MBE‐AlN may actually result in superior properties at the device level. Finally, the full HFET stack is grown by MOCVD on both types of AlN nucleation layers. Hall measurements on active devices yield comparable mobilities for both nucleation methods. Preliminary data suggest that MBE‐AlN does not have any detrimental impact the dynamic properties of the buffer. The vertical breakdown voltage measured at 1 μA mm−2 is increased by 30% and the leakage current measured at 600 V is reduced by two orders of magnitude.

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“…The activation energies of 0.42 and 0.36 eV probably are not a pure thermally induced process but a charge-transport phenomena. [20] Similarly, by using a test structure having a device layout without a gate electrode, the effect (E a ) of buffer-related trapping can be determined. The detrapping transient I D was measured at V DS ¼ 0.5 V immediately after on-state stress (V DS ¼ 10 V) was applied for 20 s under different temperatures.…”

Section: Resultsmentioning

confidence: 99%

Determination of Suitable Indicators of AlGaN/GaN HEMT Wafer Quality Based on Wafer Test and Device Characteristics

Zhong

Tang

Hsin

2017

Physica Status Solidi (a)

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This study investigates various tests on AlGaN/GaN high electron mobility transistor (HEMT) wafers, including photoluminescence spectroscopy, secondary ion mass spectroscopy, X‐ray diffraction (XRD), and Hall measurement. The AlGaN/GaN HEMT wafers are grown on low‐resistivity Si substrates with various growth conditions for the buffer and channel layers. Characteristics of AlGaN/GaN HEMTs including drain lag, dynamic RON, and current transients were measured and correlated with the results from the wafer level tests. Results indicate that epitaxial wafers with low yellow luminescence (YL) to band edge (BE) and blue luminescence (BL) to BE ratios as well as a low carbon concentration but a similar low full width at half maximum of XRD profiles can result in devices with significant suppression of current collapse and the same on‐state device characteristics. Therefore, both YL/BE and BL/BE values combined with the carbon concentration in wafer level tests are suitable indicators for estimating device performance.

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Effect of Different Carbon Doping Techniques on the Dynamic Properties of GaN-on-Si Buffers

Cited by 33 publications

References 23 publications

Suppression of Iron Memory Effect in GaN Epitaxial Layers

Suppression of Iron Memory Effect in GaN Epitaxial Layers

Impact of AlN/Si Nucleation Layers Grown Either by NH₃‐MBE or MOCVD on the Properties of AlGaN/GaN HFETs

Determination of Suitable Indicators of AlGaN/GaN HEMT Wafer Quality Based on Wafer Test and Device Characteristics

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Effect of Different Carbon Doping Techniques on the Dynamic Properties of GaN-on-Si Buffers

Cited by 33 publications

References 23 publications

Suppression of Iron Memory Effect in GaN Epitaxial Layers

Suppression of Iron Memory Effect in GaN Epitaxial Layers

Impact of AlN/Si Nucleation Layers Grown Either by NH3‐MBE or MOCVD on the Properties of AlGaN/GaN HFETs

Determination of Suitable Indicators of AlGaN/GaN HEMT Wafer Quality Based on Wafer Test and Device Characteristics

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Impact of AlN/Si Nucleation Layers Grown Either by NH₃‐MBE or MOCVD on the Properties of AlGaN/GaN HFETs