We experimentally show the possibility of fast switching and storage in GaAs-Al
xGa
1-xAs heterojunction layers in accordance with previous theoretical predictions. The switching of electrons between layers is shown to occur (at least) on a nanosecond scale. The storage times which can be accomplished are of the order of minutes at 77K and much longer at lower temperatures. These times make the effect an attractive candidate for low temperature high-speed logic applications. It is speculated that for high Al mole fraction

, storage effects can even be achieved at room temperature.