Impact of the low temperature ohmic contact process on DC and forward gate bias stress operation of GaN HEMT devices
IEEE Electron Device Letters
Institute of Electrical and Electronics Engineers
1609 - 1612
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In AlGaN/GaN high electron mobility transistors (HEMTs), high temperature processes (such as ohmic annealing with >800°C value) could deform the crystal structure and induce trap states within the bulk and surface. Expanded defect densities cause crucial problems, such as threshold voltage ( Vth ) instability, current collapse, and high leakages. In this work, a low temperature ohmic contact process (630°C, 10 minutes) is adopted with recess etch, and contact resistances <0.1Ω ⋅ mm with low sheet resistances are achieved. The positive impact of this low thermal budget process on surface morphology, DC operation, long-term stability, and forward gate bias stress of the device is studied.
Recessed 16 ohmic contacts