In0.48Ga0.52P/In0.20Ga0.80As/GaAs pseudomorphic high electron mobility transistors grown by solid-source molecular-beam epitaxy using a valved phosphorus cracker cell

In_0.48Ga_0.52P/In_0.20Ga_0.80As/GaAs pseudomorphic high electron mobility transistor (p-HEMT) structures were grown by solid-source molecular beam epitaxy (SSMBE) using a valved phosphorus cracker cell. The sheet carrier density at room temperature was 3.3 × 10¹²cm^?2. A peak transconductance (G _m) of 267 mS mm^?1 and peak drain current density (I _ds) of 360 mA mm^?1 were measured for a p-HEMT device with 1.25 µm gate length. A high gate-drain breakdown voltage (BV _gd) of 33V was measured. This value is more than doubled compared with that of a conventional Al_0.30Ga_0.70As/In_0.20Ga_0.80As/GaAs device. The drain-source breakdown voltage (BV _ds) was 12.5V. Devices with a mushroom gate of 0.25 µm gate length and 80 µm gate width achieved a peak transconductance (G _m) of 420 mS mm^?1 and drain current density of nearly 500mA mm^?1. A high cutoff frequency (f _T) of 58GHz and maximum oscillation frequency (f _max) of 120 GHz were obtained. The results showed that the In_0.48Ga_0.52P/In_0.20Ga_0.80As/GaAs material system grown by SSMBE using the valved phosphorus cracker cell for the In^0.48Ga^0.52P Schottky and spacer layers is a viable technology for high frequency p-HEMT device applications.