Photoexcitation Effects on Secondary Electron Emission from Non-NEA GaAs

Following sub-keV electron bombardment of ⟨100⟩ oriented GaAs crystals, laser-light-induced effects on kinetic secondary electron emission (SEE) have been observed for p-type, n-type, and intrinsic samples. The effects have been measured with super- and sub-bandgap lasers of wavelengths 785 nm and 976 nm, respectively. These effects were observed to vary with dopant type and photon flux. We observe increases to the SEE from intrinsic GaAs on the order of 100% and very small, <1%, changes in the emission from the p- and n-doped samples. In a separate experiment, similar effects on the SEE from intrinsic GaAs were observed by utilizing short (∼ 100 fs) electron pulses as the primary beam and a coincident electron detection scheme with a pair of channel electron multipliers. Laser induced effects were confirmed with time-resolution on the reflected and re-diffused primaries as well as true secondaries. The work presented here is aimed towards the development of novel sources of polarized electrons and a fast electron detector using this newly-discovered effect.