Observation Of A Persistent Negative Photoconductivity Effect In Algaas Gaas Modulation-Doped Structures

We report on the observation of a persistent "negative" photoconductivity effect exhibited in AlxGa1-xAs/GaAs heterostructures over the temperature range 170 < T < 300 K. We believe this to be the first observation of persistent "negative" photoconductivity, particularly at these relatively high temperatures. A possible source of the phenomenon is discussed, and suggested to originate from an interaction between the two-dimensional electron gas and EL2 centers.