Computer simulation of a new MESFET with an atomic-layer-doped structure

A new MESFET structure is proposed, utilizing atomic-layer-doping (ALD) technologies. The MESFET is constructed with both n- and p-type ALD regions: one is designed as a conducting channel and the other as a punchthrough stopper. Assuming Si ALD-MESFETs, the superiority of the threshold voltage dependence on gate length is clearly demonstrated by two-dimensional computer simulation. The threshold voltage can remain constant even in the half-micrometer range. When the punchthrough stopper is omitted from the device (which is then called a delta-FET), punch-through phenomena dominate the FET operation within the range of several micrometers, and the threshold voltage decreases sharply in that range. An optimum design concept for ALD-MESFETs using computer simulation is also discussed. When doping conditions are appropriately designed, the transconductance value can be increased slightly, over that of delta-FETs. ALD devices widen the application field of digital doping technologies using MBE and are candidates for developing half- or quarter-micrometer range devices