Improvement of Ohmic Contact for InAlGaN/AlN/GaN HEMTs with Recess Etching

Riedmüller, Sandra; Steinmann, Claudia; Grünenpütt, Jan; Scholz, F.; Blanck, H.

doi:10.1002/pssa.201700456

Cited by 4 publications

(3 citation statements)

References 20 publications

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“…4). As viewed along the [11][12][13][14][15][16][17][18][19][20] zone axis of GaN, the TiN crystallites which constitutes the main part of the phases are oriented along the [110] zone axis Figure 4: The structure and phases as distributed in the corresponding 50 nm thickness They all are surrounded by a cubic phase which is rich in Au. Towards the interface with GaN, the phases terminate with some AlGaN which can be oxidized.…”

Section: Figure 3: S2 An Overview Of the Phases In Sample S2 With The...mentioning

confidence: 99%

“…In the case of InAlN or InAlGaN, the standard values of ohmic contacts are around 0.5-0.6 Ω.mm. In order to bring the ohmic contact below 0.2 Ω.mm, complex processes have involved localized molecular beam regrowth of n+ doped GaN prior to metal deposition [16], recess to decrease the AlInN thickness in combination with specific surface treatment [17]. In the following, we report on our transmission electron microscopy investigation during the optimization of the Ti/Al/Ni/Au ohmic contact on InAlGaN/Al/GaN.…”

Section: Introductionmentioning

confidence: 99%

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Optimized ohmic contacts for InAlGaN/GaN HEMTs

Ruterana

Chauvat

Morales

et al. 2022

2022 14th International Conference on Advanced Semiconductor Devices and Microsystems (ASDAM)

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In this work, we have carried out a detailed transmission electron microscopy investigation on ohmic contacts in InAlGaN/GaN high electron mobility transistors consisting of Ti/Al/Ni/Au deposited by evaporation electron beam followed by a rapid thermal annealing at 875°C for 30s under N2 atmosphere. Subsequent to an optimized surface preparation, prior to the metal deposition, it has been possible to systematically obtain a contact resistance of 0.15-0.16 Ω.mm instead of the usual 0.5-0.6 Ω.mm. This is comparable to the state of the art results which have been published subsequent to more complex processes including molecular beam regrowth.

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Section: Figure 3: S2 An Overview Of the Phases In Sample S2 With The...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optimized ohmic contacts for InAlGaN/GaN HEMTs

Ruterana

Chauvat

Morales

et al. 2022

2022 14th International Conference on Advanced Semiconductor Devices and Microsystems (ASDAM)

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“…However, the annealing step usually used to form the metal ohmic contacts introduces metal lateral diffusion, which at some point would contact the gate. [ 11 ] High doping of the semiconductor below the metal ohmic contacts is a solution that is widely used to avoid this annealing step. Ionic implantation of Si dopant provides a high doping level if the dopant is activated by annealing at a temperature above 1000 °C.…”

Section: Introductionmentioning

confidence: 99%

Highly Si‐Doped GaN Regrown by Metal–Organic Vapor‐Phase Epitaxy for Ohmic Contact Applied to Quaternary Barrier‐Based High‐Electron‐Mobility Transistors

Pitaval

Lacam

Defrance

et al. 2023

Physica Status Solidi (a)

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The quaternary barrier InAlGaN is suitable for GaN high‐electron‐mobility transistors (HEMT) power microwave applications. High doping of the semiconductor under the drain and source is a known suitable solution to achieve low ohmic contact resistance. However, InAlGaN quaternary alloys require a low thermal budget to avoid indium desorption from the active layer during regrowth and thus deteriorating the barrier. Herein, a selective‐area growth technique at 850 °C by metal–organic vapor‐phase epitaxy (MOVPE) to achieve low contact resistance with respect to temperature constraint is presented. Regrowth temperature and mask geometry are investigated to achieve selectivity and control of the regrowth rate. The use of H2 as carrier gas decomposes the GaN buffer layer and damages the surface, creating material cluster during regrowth. Growth with N2 carrier gas shows nonselective epitaxy, as there are deposits on the entire surface of the dielectric mask. Switching from one carrier gas to another depending on the step in the MOVPE reactor helps to control both the morphology and selectivity. The resulting high doping levels of 8 × 1019 cm−3 lead to a low contact resistance of 0.26 Ω mm.

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InAlGaN-based HEMT with very low Ohmic contact resistance regrown at 850 °C by MOVPE

Pitaval,

Aroulanda,

Fouzi

et al. 2024

Applied Physics Letters

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Regrown Ohmic contacts have been widely studied for high millimeter-wave applications. However, few were applied to InAl(Ga)N-based HEMT despite the lattice match benefits with GaN channel because of the poor thermal stability of the quaternary barrier. In this article, we use relatively low temperature (850 °C) MOVPE technique for the regrowth of heavily Si doped GaN (1 × 1020 cm−3) to avoid deterioration of the channel's electrical characteristics. Moreover, high selectivity of the regrowth is obtained, thanks to large opening ratio of the hard mask. The state-of-the-art total Ohmic contact resistance Rc = 0.06 Ω mm is reached with high homogeneity on a 4-in. wafer. This result reflects the combined contribution of the doped GaN interfaces with both the metal contact and the channel. 2 × 50 μm transistors featuring 100 nm gate length with regrown Ohmic contacts present remarkable improvements of DC and RF performances. At 40 GHz, the highest Power Added Efficiency (PAE) of 54% is attained at an output power of 3.8 W mm−1, while the maximum output power of 9.4 W mm−1 is achieved at a PAE of 48%, corresponding to bias voltages of 15 and 30 V, respectively.

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Improvement of Ohmic Contact for InAlGaN/AlN/GaN HEMTs with Recess Etching

Cited by 4 publications

References 20 publications

Optimized ohmic contacts for InAlGaN/GaN HEMTs

Optimized ohmic contacts for InAlGaN/GaN HEMTs

Highly Si‐Doped GaN Regrown by Metal–Organic Vapor‐Phase Epitaxy for Ohmic Contact Applied to Quaternary Barrier‐Based High‐Electron‐Mobility Transistors

InAlGaN-based HEMT with very low Ohmic contact resistance regrown at 850 °C by MOVPE

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