As semiconductor devices are scaled down to the nanometre level, random dopant fluctuation in the conducting channel caused by the small number of dopant atoms will significantly affect device performance. We fabricated semiconductor devices with random discrete dopant distribution in the drain side and then evaluated how well we could control the drain current of the devices. The results showed that the drain current in devices with the dopant distribution in the drain side was several per cent higher than that in devices with the dopant distribution in the source side. We believe that this increase in current is caused by the suppression of injection velocity degradation in the source side. The capability to control the location of individual dopant atoms enhances drain current and, therefore, the performance of nanodevices. Accurately controlling both the amount and the positioning of dopant atoms is critical for the advancement of true nanoelectronics.