A novel GaAs current-controlled bipolar-unipolar transition negative differential resistance transistor prepared by molecular-beam epitaxy

Abstract GaAs current-controlled bipolar-unipolar transition negative differential resistance (NDR) transistors using n+-i-p+-i-n+ structure prepared by molecular-beam epitaxy (MBE) are demonstrated. Using a base thickness of 200 Å and a highly doped sheet concentration of 1013 cm−2, a NDR phenomenon is revealed at base low injection level. The peak-to-valley current ratios are about eight at room temperature. This is proposed to be due to the bipolar-unipolar transition reaction. When the base is under a high injection level, the proposed device operates just like a conventional bipolar transistor. A hypothetical model is used and confirmed by experiments.