Investigation of GaN channel thickness on the channel mobility in AlGaN/GaN HEMTs grown on sapphire substrate

Chang, Sung‐Jae; Bhuiyan, Mansurul; Won, Chul-Ho; Lee, J.-H.; Jung, Hyun‐Wook; Shin, Min Jeong; Do, Jae-Won; Cho, K. J.; P., T.; Lim, Jong−Won

doi:10.1109/rfit.2017.8048091

Cited by 2 publications

(1 citation statement)

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“…The advantage of the SiC over GaN substrates is higher SiC thermal conductivity and therefore potentially better thermal management of the transistors fabricated using AlGaN/GaN/SiC structures. The common approach to compensate for lattice mismatch and to reduce the dislocation density in these structures is to grow the aluminium gallium nitride (AlN) nucleation layer (NL) with reduced crystalline quality followed by a several-micrometres-thick GaN buffer doped with deep acceptors such as Fe or C which compensate for residual doping of an n -type GaN [ 10 , 11 , 12 ]. However, this approach deteriorates the overall thermal resistance of the structure and diminishes the advantage of a SiC substrate operating as a heatsink [ 13 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

AlGaN/GaN on SiC Devices without a GaN Buffer Layer: Electrical and Noise Characteristics

et al. 2020

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We report on the high-voltage, noise, and radio frequency (RF) performances of aluminium gallium nitride/gallium nitride (AlGaN/GaN) on silicon carbide (SiC) devices without any GaN buffer. Such a GaN–SiC hybrid material was developed in order to improve thermal management and to reduce trapping effects. Fabricated Schottky barrier diodes (SBDs) demonstrated an ideality factor n at approximately 1.7 and breakdown voltages (fields) up to 780 V (approximately 0.8 MV/cm). Hall measurements revealed a thermally stable electron density at N2DEG = 1 × 1013 cm−2 of two-dimensional electron gas in the range of 77–300 K, with mobilities μ = 1.7 × 103 cm2/V∙s and μ = 1.0 × 104 cm2/V∙s at 300 K and 77 K, respectively. The maximum drain current and the transconductance were demonstrated to be as high as 0.5 A/mm and 150 mS/mm, respectively, for the transistors with gate length LG = 5 μm. Low-frequency noise measurements demonstrated an effective trap density below 1019 cm−3 eV−1. RF analysis revealed fT and fmax values up to 1.3 GHz and 6.7 GHz, respectively, demonstrating figures of merit fT × LG up to 6.7 GHz × µm. These data further confirm the high potential of a GaN–SiC hybrid material for the development of thin high electron mobility transistors (HEMTs) and SBDs with improved thermal stability for high-frequency and high-power applications.

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