Heterojunction ion-implanted FETs (HIFETs)

Summary form only given. The authors report the enhanced microwave performance of ion-implanted MESFETs fabricated on graded GaAs-AlGaAs heterostructures. Since low-noise MESFETs are typically biased at a low drain current, optimum low-noise operation requires high f₁ at low drain currents. f_t values reported in the literature are generally measured close to I_dss. This 0.5- mu m gate heterojunction ion-implanted FET (HIFET) exhibits enhanced microwave performance, especially at low drain current, when compared to conventional ion-implanted GaAs MESFETs. At 20% of I_dss, the current gain cutoff frequency f_t is 40 GHz, which increases to 47 GHz at 50% of I_dss. At 100% of I_dss, the f_t is 41 GHz. The maximum stable gain at 25 GHz of the HIFET is also 4 dB higher than that of the conventional MESFET.