The study of negative differential resistance phenomenon in a two-step barrier diode

In this work, the realization of a Al/sub x/Ga/sub 1-x/As/GaAs two-step barrier diode is presented. Experimental observation on the current-voltage (I-V) characteristics of the two-step barrier diode is reported for the first time. At both room temperature and 77 K, it shows a strong negative differential resistance (NDR) under forward bias while no similar phenomenon was observed under reverse bias. Such an asymmetric I-V characteristic would open the possibility of NDR in an ac field in the absence of a dc bias. Theoretical simulation and experimental I-V characteristics are compared and discussed.