A Novel Functional Negative-Differential-Resistance Heterojunction Bipolar Transistor (NDR-HBT)

摘要

A novel functional negative-differential-resistance heterojunction bipolar transistor (NDR-HBT) has been successfully fabricated and demonstrated. The studied device acts as a conventional HBT for the applied higher base current of I_B=100μA/step. However, the NDR phenomenon with interesting topee-shaped current-voltage characteristics was observed under the applied base current of I_B=2μA/step. These are attributed to the use of narrow base width and δ-doped sheet in the studied device. Besides, the N-shaped NDR phenomena are obviously observed under the applied tungsten light source. The peak-to-valley current ratio (PVCR) up to 1.5 is obtained for the base current I_B=60μA. The photocurrent is about 1.01mA and keeps constantly under the applied higher base current.