Owing to a larger bandgap and a higher breakdown field, higher emissio
n efficiency and emission current density have been obtained from Al0.
3Ga0.7As planar-doped-barrier electron emitters (PDBEEs) compared with
GaAs PDBEEs. Preliminary experiments gave an emission efficiency of 1
% and a current density of 2.6Acm-2 from a 5 x 144mum2 emission region
with an anode bias of 100 V. Further improvement of the device perfor
mance can be achieved by optimising the device design and surface acti
vation process.