A small collector-up AlGaAs/GaAs heterojunction bipolar transistor fabricated using H+ implantation

A small collector-up AlGaAs/GaAs heterojunction bipolar transistor with a collector size of 1 x 10 μ2 is developed by making the entire emitter layer under the external base highly resistive by oblique H+ implantation from both sides along the elongated direction of the collector mesa, and by forming the collector electrode and base electrodes by selfalignment method. The transistor shows high-frequency properties of fT = 31 GHz and fmax = 50 GHz. The relationship between the process used and the properties of the transistor is analyzed. (author)