CHARACTERIZATION OF A GAAS CURRENT-CONTROLLED BIPOLAR-UNIPOLAR TRANSITION NEGATIVE DIFFERENTIAL RESISTANCE TRANSISTOR

GaAs current-controlled bipolar-unipolar transition negative differential resistance (NDR) transistors using an n+-i-p+-i-n + homojunction structure prepared by molecular beam epitaxy are demonstrated. For a base thickness of 200 Å and using a highly doped sheet concentration of 1013 cm-2, a NDR region is revealed for IB<100 μA. The peak-to-valley current ratios are about 8 at room temperature. This is proposed to be due to the bipolar-unipolar transition reaction. When IB>=100 μA, the proposed device operates as a conventional bipolar transistor. Additionally, the effects of base thickness on current-voltage characteristics are also investigated.