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

The effect of the position of the δ -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 δ -doping is placed below the channel. If the same amount of the δ -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 δ -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 δ -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 δ -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 δ -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.