While a wide bandgap material with poor mobility can saturate the output current, we demonstrate a way to achieve clear current saturation in the output characteristics using narrow-bandgap, high mobility graphitic-channels(Fig.4b, 4c) without hurting the mobility. Using gate engineering alone, we preserve the intrinsic narrow bandgap but locally cascade them along the channel. This filters intermediate conduction and valence bands and widens the gap in the tranmission (Fig.3) without sacrificing mobility. A widen transmission gap delays the onset of band-to-band tunneling, which normally plagues devices with a narrow bandgap channel. Results are verified using an optimized fully atomistic non-equilibrium Green's Function(NEGF) solver with complex 3-D Poisson1. A graphitic channel is used as a template but is one of many possible narrow-bandgap materials with high mobility. Without hurting mobility, the improved current saturation is expected to enhance gain for radio frequency(RF) and potentially digital switching applications by significantly decreasing output conductance(gds)2.
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