Charging efficiency and lifetime of image-bound electrons on a dielectric surface

The surface charge generated on an Al0.24Ga0.76As/GaAs quantum well sample by electron bombardment was monitored by measuring the change in the conductivity of the channel. Upon turning off the electron bombardment the surface charge on adsorbed layers of xenon and water at 8 K decays in room. temperature darkness with a lifetime τ=0.30± 0.02 s. The average charging efficiency, μ(0), defined as the ratio of the charge collected by the surface to the beam current times the charging time, is μ(0) ≃ 0.001. Surface charging proves to be an effective method for contactless gating of field effect devices. © 2005 American Institute of Physics.