Single Heterostructures for Optical Transport Experiments.

We introduce a new GaAs/Al sub x Ga sub 1-sub x As single heterostructure, which allows local optical injection of a one-component confined plasma. The heterojunction is placed in the undoped region of a p-i-n structure, which provides a high built-in electric field for the separation of injected electrons and holes, as well as for the two- dimensional confinement of electrons. A time-of-flight measurement of the majority-electron drift velocity at room temperature is demonstrated.