A novel normally-off camel diode gate GaAs field-effect transistor

A novel normally-off GaAs field-effect transistor utilizing a "camel diode" in place of a Schottky barrier and exhibiting excellent properties was demonstrated. The devicies have channel lengths of 3 or 4 μm, gate lengths of approximately 3 or 4 μm, and gate widths of 290 μm. The layers from which the devices were fabricated were prepared by molecular beam epitaxy and consisted of a 1-μm-thick Al _0.3 Ga _0.7 As buffer, an ∼500-Å GaAs layer doped to a level of 1.5×10 ¹⁷ cm ^-3 to form the channel, and 100-Å p ⁺ Al _0.47 Ga _0.53 As and 400-Å n ⁺ GaAs layers to form the gate. The devices exhibited transconductances as high as 80 mS/mm and excellent saturation characteristics.