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

Abstract

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.