Investigation of hot‐electron injection and ballistic transport using ultrathin planar doped barrier launchers in vertical field effect spectrometer structures

A study in the optimization of ultrathin planar doped barriers (PDB) for use as hot‐electron/ballistic electron launchers in vertical field effect spectrometer structures was conducted. A comparison was made of results for an all‐PDB (PDB launcher/PDB analyzer) versus a PDB launcher/graded AlGaAs spectrometer. Previous work involving PDB launchers and vertical field effect structures predicted little to no enhancement of electron current density. This study conclusively refutes these predictions. A new analyzer‐up‐top design scheme as well as optimization experiments involving varying PDB layer and associated drift region thickness were developed. This work shows previously unobserved hot electron/ballistic spectra for these structures. Moreover, high current densities in excess of 105 A/cm2 were observed for the all‐PDB and for the ultra‐thin PDB launcher/graded AlGaAs spectrometers under conditions involving both thermionic emission and tunneling.