Ion-implanted In_0.1Ga_0.9 As metal-semiconductor field-effect transistors on GaAs (100) substrates

Ion-implanted In_0.1Ga_0.9As metal-semiconductor field-effect transistors (MESFETs) have been fabricated on 3 in. GaAs (100) substrates. The structure comprises an undoped InGaAs epitaxially layer grown directly on a GaAs (100) substrate by the metalorganic chemical vapor deposition (MOCVD) technique. Si⁺²⁸ is ion implanted into the InGaAs layer to form an active channel layer. MESFETs with 100 μm gate width and 0.5 μm gate length are fabricated using standard process techniques. The best device shows a maximum transconductance of 426 mS/mm. From S-parameter measurements, the current-gain cutoff frequency f_t is 37 GHz and the maximum available gain cutoff frequency f_max is 85 GHz. These results are comparable to InGaAs MESFETs grown by MBE.