Ion-implantation technology for improved GaAs MESFETs performance

Electrical properties of Si-implanted and co-implanted with Mg or Be in semi-insulating GaAs was studied. The Si-implanted MESFETs with and without buried p-layer (formed by Mg or Be) have been fabricated and characterized by their d.c. and r.f. performance. The experimental results showed that the device with a buried p-layer can effectively suppress the substrate leakage current (thus good pinch-off characteristic) and obtained higher gain linearity than these without a buried p-layer. For 1 mum x 100 mum MESFETs device with co-implantation of Si (similar to 8 x 10(12) cm(-2)) and Be (similar to 6 x 10(11) cm(-2)) demonstrated uniform transconductance (g(m)) of similar to 115 mS mm(-1) with the gate voltage ranging from - 1 to 1 V and reduced pinch-off voltage compared to those with co-implantation of Si and Mg (similar to 6 x 10(11) cm(-2)). The measured f(T) and f(max) of a 1 mum x 25 mum MESFET with co-implantation of Si and Be are 10 and 39 GHz, respectively. However, FETs with increased Mg dose (from 6 x 10(11) cm(-2) to 2 x 10(12) cm(-2)) in a buried p-layer can obtain higher transconductance and saturation current. (C) 2004 Kluwer Academic Publishers.