Gate length scaling behavior and improved frequency characteristics of In0.8Ga0.2As high-electron-mobility transistor, a core device for sensor and communication applications

초록

The impact of the gate length (L<inf>g</inf>) on the DC and high-frequency characteristics of indium-rich In<inf>0.8</inf>Ga<inf>0.2</inf>As channel high-electron mobility transistors (HEMTs) on a 3-inch InP substrate was inverstigated. HEMTs with a source-to-drain spacing (L<inf>SD</inf>) of 0.8 μm with different values of L<inf>g</inf> ranging from 1 μm to 19 nm were fabricated, and their DC and RF responses were measured and analyzed in detail. In addition, a T-shaped gate with a gate stem height as high as 200 nm was utilized to minimize the parasitic gate capacitance during device fabrication. The threshold voltage (V<inf>T</inf>) roll-off behavior against L<inf>g</inf> was observed clearly, and the maximum transconductance (g<inf>m_max</inf>) improved as L<inf>g</inf> scaled down to 19 nm. In particular, the device with an L<inf>g</inf> of 19 nm with an L<inf>SD</inf> of 0.8 mm exhibited an excellent combination of DC and RF characteristics, such as a g<inf>m_max</inf> of 2.5 mS/μm, On resistance (R<inf>ON</inf>) of 261 Ω•μm, current-gain cutoff frequency (f<inf>T</inf>) of 738 GHz, and maximum oscillation frequency (f<inf>max</inf>) of 492 GHz. The results indicate that the reduction of L<inf>g</inf> to 19 nm improves the DC and RF characteristics of InGaAs HEMTs, and a possible increase in the parasitic capacitance component, associated with T-shap, remains negligible in the device architecture. © 2021, Korean Sensors Society. All rights reserved.

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