Enhancement-Mode InAlAs/InGaAs/InP High Electron Mobility Transistor with Strained InAlAs Barrier Layer

The relatively low Schottky barrier height on In_0.52Al_0.48As lattice-matched to InP has hampered the achievement of enhancement-mode InAlAs/InGaAs/InP high electron mobility transistors (E-HEMTs). By introducing lattice-mismatched strained aluminum-rich In_0.45Al_0.55As as the Schottky contact material to enhance the barrier height, we have developed InP-based InAlAs/InGaAs/InP E-HEMT with threshold voltage of about 150mV. A maximum extrinsic transconductance of 660mS/mm and output conductance of 15 mS/mm are measured for 1 μm-gate-length devices at room temperature. The devices also show excellent radio-frequency performance with cutoff frequency of 50 GHz and maximum oscillation frequency of 54 GHz.