Effect of strain relaxation on the drain conductance in AlGaN/GaN HEMTs

Bellakhdar, A.; Telia, A.; Semra, L.; Soltani, A.

doi:10.1109/icengtechnol.2012.6396129

Cited by 2 publications

(2 citation statements)

References 7 publications

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“…1. It is stated in [48] that for a heterostructure containing AlGaN barrier, whose thickness is in the range of 20-40 nm is expected to be fully strained for 0 ≤ x ≤ 0.38, partially relaxed for 0.38 ≤ x ≤ 0.67, and fully relaxed for 0.67 ≤ x ≤ 1. Further it is reported in [49], AlGaN layer with mole-fraction, x > 0.4 and x < 0.15 are not applicable for high quality HFETs.…”

Section: Numerical Simulation/physical Modelmentioning

confidence: 99%

Introspection Into Reliability Aspects in AlGaN/GaN HEMTs With Gate Geometry Modification

2021

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Reliability enhancement of AlGaN / GaN HEMT is a significant thrust area due to rapidly improving material and processing technology. In this paper, a detailed analysis of gate-shaped AlGaN / GaN HEMT with field plate is presented. Although AlGaN / GaN HEMT with field-plate is well known, its blending with gate-shaping leading to a more robust and reliable behaviour is described in this paper. It is observed that the threshold voltage and transconductance invariably remain constant for various combinations of gate-shaped and field plate placements. The threshold voltage for all the devices are found to be -5.8 V. The peak transconductance for the devices without field plate and with field plate is ∼ 0.16 S/mm and ∼ 0.15 S/mm, respectively. Apart from leakage current, the electric field also gets mitigated for both gate-shaped and field-plated devices by ∼ 45% and ∼ 68%, respectively. The moderation in electric field further assists in the reduction of electron temperature for gate-shaped and field-plated structures by ∼ 12% and ∼ 85%, respectively. Additionally, breakdown voltage increases for the gate-shaped devices to 133 V as compared to 120 V of conventional devices without field plate. Significant reduction in leakage current, electric field, and electron temperature is accompanied by a minor increment in capacitance for the field-plated structure, hence, the proposed structure is expected to enhance reliability of the device. Thus, it is anticipated that the proposed devices with enhanced reliability would be a step ahead of conventional devices and would find major applications in high power domain.INDEX TERMS Capacitance voltage (CV), electron temperature, GaN HEMT, gate shape, leakage current.

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Section: Numerical Simulation/physical Modelmentioning

confidence: 99%

Introspection Into Reliability Aspects in AlGaN/GaN HEMTs With Gate Geometry Modification

2021

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“…In‐plane strain across the heterojunction results in a critical thickness depending on Al x Ga 1– x N barrier layer alloy content . Beyond this, strain relaxation diminishes the piezoelectric polarisation component reducing the 2DEG carrier density , and suppresses mobility through the introduction of scattering from defect centres . Redistribution of strain has been reported to manifest as features on the wafer surface on the micro‐ and nanoscale .…”

Section: Introductionmentioning

confidence: 99%

Nanoscale fissure formation in Al_xGa_1–xN/GaN heterostructures and their influence on Ohmic contact formation

Smith¹,

Thomson

Zubialevich³

et al. 2016

Physica Status Solidi (a)

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Nanoscale surface fissures on AlxGa1–xN/GaN (15 nm/1 µm) heterostructures grown by metalorganic vapour phase epitaxy (MOVPE) were imaged using tapping‐mode atomic force microscopy (AFM) and electron channelling contrast imaging (ECCI). Fissure formation was linked to threading dislocations, and was only observed in samples cooled under H2 and NH3, developing with increasing barrier layer Al content. No strain relaxation was detected regardless of fissure formation up to barrier layer Al composition fractions of x = 0.37. A reduction of measured channel carrier density was found in fissured samples at low temperature. This instability is attributed to shallow trap formation associated with fissure boundaries. For Ti/Al/Ni/Au Ohmic contact formation to high Al content barrier layers, fissures were found to offer conduction routes to the 2DEG that allow for low resistance contacts, with fissure‐free samples requiring additional optimisation of the metal stack and anneal conditions to achieve contact resistivity of order those measured in fissured samples. In addition, the effects of fissures were found to be detrimental to thermal stability of sheet and contact resistance, suggesting that fissure formation compromises the integrity of the 2DEG.

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Effect of strain relaxation on the drain conductance in AlGaN/GaN HEMTs

Cited by 2 publications

References 7 publications

Introspection Into Reliability Aspects in AlGaN/GaN HEMTs With Gate Geometry Modification

Introspection Into Reliability Aspects in AlGaN/GaN HEMTs With Gate Geometry Modification

Nanoscale fissure formation in Al_xGa_1–xN/GaN heterostructures and their influence on Ohmic contact formation

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Effect of strain relaxation on the drain conductance in AlGaN/GaN HEMTs

Cited by 2 publications

References 7 publications

Introspection Into Reliability Aspects in AlGaN/GaN HEMTs With Gate Geometry Modification

Introspection Into Reliability Aspects in AlGaN/GaN HEMTs With Gate Geometry Modification

Nanoscale fissure formation in AlxGa1–xN/GaN heterostructures and their influence on Ohmic contact formation

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Nanoscale fissure formation in Al_xGa_1–xN/GaN heterostructures and their influence on Ohmic contact formation