Mechanism and enhancement of the near-threshold low OFF-state breakdown voltage in gallium nitride high electron mobility transistors

We studied AlGaN/GaN high electron mobility transistors grown on a SiC substrate. They had a hard breakdown voltage VBR ≥ 70 V under a deep OFF-state with a much less and softer VBR ∼ 27 V for near-threshold OFF-state gate bias conditions. We established that the low, soft breakdown is due to space...

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Bibliographic Details
Published in:Japanese Journal of Applied Physics 2019-06, Vol.58 (SC), p.SCCD01
Main Authors: Prasannanjaneyulu, Bhavana, Bhattacharya, Sudipto, Karmalkar, Shreepad
Format: Article
Language:English
Subjects:
Aluminum gallium nitrides
Avalanches
Breakdown
Computer simulation
Density
Electric potential
Energy levels
Gallium nitrides
High electron mobility transistors
Semiconductor devices
Space charge
Substrates
Transistors
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Summary:We studied AlGaN/GaN high electron mobility transistors grown on a SiC substrate. They had a hard breakdown voltage VBR ≥ 70 V under a deep OFF-state with a much less and softer VBR ∼ 27 V for near-threshold OFF-state gate bias conditions. We established that the low, soft breakdown is due to space charge limited current (SCLC) from drain to source via the GaN buffer, which has deep traps. Previous works had established the presence of SCLC from bulk to gate and drain to gate. For the first time we establish drain to source SCLC. We achieved this by analyzing the IDS-VDS data extracted from the measured IS-VDS. We determined the following by numerical simulation: (a) the density and energy level of traps causing the observed SCLC; (b) the minimum trap density required to suppress the SCLC and raise the VBR up to the avalanche limit for the whole OFF-state regime for devices with a channel length down to 0.15 m.
ISSN:0021-4922
1347-4065
DOI:10.7567/1347-4065/ab07a6