gate resistance, MODFET, MESFET, skin effectWe discuss in depth a previously overlooked component in the gate resistance Rg of SchottkyBarrier-Gate FETs, in particular 0.1-µm gate-length AlInAs/GaInAs MODFETs. The high-frequency noise and power gain of these FETs depends critically on Rg. This has been the motivation for the development of T-gates which keep the gate finger metallization resistance Rga (proportional to the gate width Wg) low, even for very short gate length Lg. Rga increases with frequency due to the skin effect, but our 3D numerical modeling shows conclusively that this effect is negligible. We show that the always "larger-thanexpected" Rg, is instead caused by a component Rgi which scales inversely with Wg. We interpret Rgi as a metal-semiconductor interfacial gate resistance. The dominance of Rgi profoundly affects device optimization and model scaling. For GaAs and InP based SBGFETs there appears to exist a smallest practically achievable normalized interfacial gate resistance rgi on the order of 10 -7 Ωcm 2 .
AbstractWe discuss in depth a previously overlooked component in the gate resistance R g of Schottky-Barrier-Gate FETs, in particular 0.1-µm gate-length AlInAs/GaInAs MODFETs.The high-frequency noise and power gain of these FETs depends critically on R g . This has been the motivation for the development of T-gates which keep the gate finger metallization resistance R ga (proportional to the gate width W g ) low, even for very short gate length L g . R ga increases with frequency due to the skin effect, but our 3D numerical modeling shows conclusively that this effect is negligible. We show that the always "larger-thanexpected" R g , is instead caused by a component R gi which scales inversely with W g . We interpret R gi as a metal-semiconductor interfacial gate resistance. The dominance of R gi profoundly affects device optimization and model scaling. For GaAs and InP based SBGFETs there appears to exist a smallest practically achievable normalized interfacial gate resistance r gi on the order of 10 -7
Ωcm2 .