A high performance GaAsp‐metal‐semiconductor field‐effect transistor (MESFET) using carbon as thep‐dopant is demonstrated. The channel and contact layers were grown by metalorganic molecular beam epitaxy (MOMBE). The cap contact layer was highly doped with carbon (5×1020cm−3) in order to minimize the parasitic resistance in the FET structure. The sheet resistivity and transfer resistance of the contacts were 220 &OHgr;/&laplac; and 0.2 &OHgr; mm, respectively. These are comparable to values achieved onn‐type GaAs. The room temperature extrinsic transconductance andK‐factor values were 50 mS/mm and 165 mS/V⋅mm with 1 &mgr;m gate length and 3.5 &mgr;m source‐to‐drain spacings. These are the highest room temperature values ever demonstrated forp‐GaAs MESFET.