A heterostructure field-effect transistor with an n(+)-GaAs/p(+)-InGaP/n-GaAs high-barrier gate and n-GaAs/i-InGaAs/i-GaAs/delta-doped sheet heterostructure channel (device A) has been successfully fabricated and studied. The heavily doped p(+)-InGaP layer and heterostructure channel are introduced to increase the barrier height and carrier confinement, respectively. Experimentally, the device without the high-barrier gate structure (device B) is also fabricated for comparison to investigate the influence of high-barrier gate structure on device characteristics. Due to the high-barrier gate added to suppress the tunneling current in device A, the gate leakage current is also substantially reduced. Therefore, the turn-on voltage, breakdown voltage, current drivability, and transconductance linearity are all significantly improved for device A relative to device B. Furthermore, the temperature-dependent characteristics of device A are also improved.