Possible ballistic effects in GaAs current limiters

Two-terminal N+NN+ current limiters have been fabricated in GaAs by selective ion-implantation of the N+ and N regions into undoped substrate material. Voltage-current characteristics have been measured at 77°K, 300°K and 400°K and reveal current limiting properties above about 0.8 to 1.0 volts at all three temperatures. In the voltage range below 0.7 volts a relation of I ~ V^{3/2}was observed for the devices operating at 77°K. Such a variation has been suggested as being indicative of ballistic motion of electrons when taking into consideration that the distance between the N+ regions is in the range of 0.5 to 0.8µm and the doping concentration of the N region is about 10¹⁶cm^-3.