InGaAs/GaAs planar doped barrier electron emitters

Emission from planar doped barrier (PDB) hot electron generators is demonstrated. The PDB structure consists of a sequence of n/sup +/-i- delta (p/sup +/)-i-n/sup + /layers. The delta (p/sup +/) layer is fully depleted, giving rise to a triangular barrier. An applied bias V forward biases the n/sup +/-i- delta (p/sup +/) junction while reverse biasing the delta (p/sup +/)-i-n/sup + /junction, much like the distribution of emitter-collector bias applied to a bipolar transistor with a fully depleted base. The reverse bias potential accelerates the electrons injected over the semiconductor barrier to a maximum kinetic energy determined by the applied potential. The final kinetic energy is lowered by scattering processes. The intrinsic efficiency of emission is therefore determined by quasi-ballistic transport across the acceleration region of the diode.