Monte Carlo simulations of δδ-doping placement in sub-100 nm implant free InGaAs MOSFETs

The effect of the position of the δδ-doping layer(s) on performance of III–V heterostructure MOSFET is investigated using Monte Carlo simulations. A 100 nm gate length MOSFET with an In0.2 Ga0.8 As channel delivers a drive current of 600 μ A/μ m at a 0.5 V overdrive when the δδ-doping is placed below the channel. If the same amount of the δδ-doping is placed above the channel, the drive current increases to 900 μ A/μ m at the same overdrive and the threshold voltage increases by 0.5 V. When two δδ-doped layers are placed below and above the channel, the drive current drops to 580 μ A/μ m at the 0.5 V overdrive and the threshold voltage decreases by 0.4 V. When the implant free MOSFET with the δδ-doped layer placed below the channel is scaled proportionally to gate lengths of 70 and 50 nm the drive current increases to 1125 and 1400 μ A/μ m, respectively. When the δδ-doped layer is placed above the channel the drive current in the corresponding 70 and 50 nm transistors rises to 1350 and 1500 μ A/μ m, respectively. However, the double δδ-doped 70 and 50 nm MOSFETs could deliver a drive current of 1000 and 1300 μ A/μ m, respectively, which is complemented by a 0.4 V threshold voltage shift.