IEEE Journal of the Electron Devices Society (Jan 2020)
In₀.₅₃Ga₀.₄₇As/InAs Composite Channel MOS-HEMT Exhibiting 511 GHz <italic>f<sub>τ</sub></italic> and 256 GHz <italic>f</italic><sub>max</sub>
Abstract
In0.53Ga0.47As/InAs composite channel MOS-HEMT exhibiting peak fτ = 511 GHz and peak fmax = 285 GHz is demonstrated. Additionally, another device exhibiting peak fτ = 286 GHz and peak fmax = 460 GHz is reported. The devices have a 1 nm / 3 nm AlxOyNz interfacial layer and ZrO2 gate dielectric on a 2 nm / 4 nm In0.53Ga0.47As/InAs / InAs composite channel with a modulation doped In0.52Al0.48As back barrier. To reduce parasitic gate-source and gate-drain capacitances, a modulation doped In0.52Al0.48As / In0.53Ga0.47As/InAs / InAs composite quantum well is included between the gate edges and the N+ source and drain. Compared to the work of Wu et al., addition of an In0.52Al0.48As back-barrier, scaling of S/D metal spacing, and scaling of channel thickness has enabled improved transconductance and increased fτ. Short gate length devices fmax are limit by high RG due to poor metal filling of the T-Gate stem and large CDS due to a conductive etch stop layer. Long gate length devices exhibit better metal filling, reduced RG, and balanced fτ, fmax. Devices exhibit 10-15% DC-1 GHz gm,e suggesting that the high-k / semiconductor interface has low Dit.
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