The effects of p co-implants upon the RF performance of ion-implanted GaAs power FETs

The use of p-type co-implants to improve GaAs MESFET performance has been examined using a physically based, analytic large-signal device model. The p dopants are shown to affect RF performance by altering both the shape and conduction characteristics of the channel. The p dopants improve channel charge confinement, but reduce the electron transport characteristics. RF performance degradation due to the reduced mobility and saturation velocity can be compensated by increasing the drain bias, since BV/sub gd/ is increased. The result if that RF performance comparable to that of similar devices fabricated without the p co-implants is obtained. The model is verified by comparison with measured RF data of an X-band MESFET.<>