Mass Transport Regrowth of GaN for Ohmic Contacts to AlGaN/GaN

Heikman, S.; Keller, S.; Moran, B.; Coffie, R.; DenBaars, Steven P.; Mishra, Umesh K.

doi:10.1002/1521-396x(200111)188:1<355::aid-pssa355>3.0.co;2-h

Cited by 5 publications

(3 citation statements)

References 8 publications

(8 reference statements)

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“…In this figure, many island‐like structures are generated and the surface morphology becomes rough. There are some reports about mass transport of GaN and AlGaN during annealing process . However, for the samples shown in Figure , we have confirmed that the configurations of the recess structures, such as the depth or inclined angle at edge of recess, were not changed by the thermal treatment.…”

Section: Resultssupporting

confidence: 58%

Improvement of Channel Mobility of GaN‐MOSFETs With Thermal Treatment for Recess Surface

Uesugi

Shindome

Kajiwara

et al. 2017

Physica Status Solidi (a)

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In this work, a thermal treatment technique under NH3 ambient for the recess surface of GaN‐MOSFETs is developed. Immediately following the fabrication process of the recess, the bottoms of these structures have rough surfaces and step‐terrace structures cannot be observed because of the plasma‐induced damage. However, clear step‐terrace structures are formed by the thermal treatment, and the RMS values of the surface roughness decrease from 0.26 to 0.14 nm, which is comparable to those of the as‐grown epitaxial film. In addition, it is confirmed that concentrations of impurity atoms introduced during the recess fabrication process are decreased by the thermal treatment. The channel mobility of the GaN‐MOSFETs without the thermal treatment is 118 cm2 Vs−1, whereas that of the device whose fabrication process includes the thermal treatment increased to 149 cm2 Vs−1. These results indicate that the thermal treatment under NH3 ambient is effective for reducing on‐state resistance of GaN‐MOSFETs.

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Section: Resultssupporting

confidence: 58%

Improvement of Channel Mobility of GaN‐MOSFETs With Thermal Treatment for Recess Surface

Uesugi

Shindome

Kajiwara

et al. 2017

Physica Status Solidi (a)

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“…2D layer growth at the p-GaN surface and the trench bottom dominates for large L AP , forming an imprint of the original trench. But also, mass transport from the p-GaN surface to the trench sidewall is occurring, as indicated in gray in Figure 2c [27]. This leads to small sidewall angles, a different surface morphology and a planarization of the trench.…”

Section: Methodsmentioning

confidence: 98%

Comparison of MOCVD and MBE Regrowth for CAVET Fabrication

et al. 2019

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In this paper, we demonstrate the fabrication of current aperture vertical electron transistors (CAVET) realized with two different epitaxial growth methods. Templates with a p-GaN current blocking layer (CBL) were deposited by metal organic chemical vapor deposition (MOCVD). Channel and barrier layers were then regrown by either molecular beam epitaxy (MBE) or MOCVD. Scanning electron microscope (SEM) images and atomic force microscope (AFM) height profiles are used to identify the different regrowth mechanisms. We show that an AlN interlayer below the channel layer was able to reduce Mg diffusion during the high temperature MOCVD regrowth process. For the low-temperature MBE regrowth, Mg diffusion was successfully suppressed. CAVET were realized on the various samples. The devices suffer from high leakage currents, thus further regrowth optimization is needed.

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“…Multiple technologies have been tried, including implantation, 5) multi-channels, 6) and regrown ohmic regions. 7) Some groups also used an n þ GaN cap structure to decrease access resistance, which required annealed ohmic contacts. 8) Rough ohmic edge after annealing prevented further shrinking of the source to drain distance, limiting a further decrease of the access resistance.…”

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confidence: 99%

Study of the n⁺ GaN Cap in AlGaN/GaN High Electron Mobility Transistors with Reduced Source–Drain Resistance

Pei¹,

Shen²,

Palacios³

et al. 2007

jjap

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An n þ GaN cap layer has been applied on an AlGaN/GaN high electron mobility transistor (HEMT) to achieve a non-alloyed ohmic contact. Delta dopings were used at the heterointerface of the n þ GaN cap and AlGaN layer to lower the AlGaN potential barrier and to improve communication between the n þ GaN cap and the two-dimensional electron gas (2DEG) channel. Non-alloyed ohmic contact resistance as low as 0.2 Ámm, and sheet resistance of 60 /Ã were achieved. Selective etch and sidewall technology were applied during processing. The n þ capped device was fabricated and compared to a standard AlGaN/GaN HEMT. Lower on-resistance and access resistance, higher f and f MAX , and better linearity in terms of g m were achieved.

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Mass Transport Regrowth of GaN for Ohmic Contacts to AlGaN/GaN

Cited by 5 publications

References 8 publications

Improvement of Channel Mobility of GaN‐MOSFETs With Thermal Treatment for Recess Surface

Improvement of Channel Mobility of GaN‐MOSFETs With Thermal Treatment for Recess Surface

Comparison of MOCVD and MBE Regrowth for CAVET Fabrication

Study of the n⁺ GaN Cap in AlGaN/GaN High Electron Mobility Transistors with Reduced Source–Drain Resistance

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Mass Transport Regrowth of GaN for Ohmic Contacts to AlGaN/GaN

Cited by 5 publications

References 8 publications

Improvement of Channel Mobility of GaN‐MOSFETs With Thermal Treatment for Recess Surface

Improvement of Channel Mobility of GaN‐MOSFETs With Thermal Treatment for Recess Surface

Comparison of MOCVD and MBE Regrowth for CAVET Fabrication

Study of the n+ GaN Cap in AlGaN/GaN High Electron Mobility Transistors with Reduced Source–Drain Resistance

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Study of the n⁺ GaN Cap in AlGaN/GaN High Electron Mobility Transistors with Reduced Source–Drain Resistance