Observation of doping profiles in Gunn diodes with a scanning electron microscope using the $\beta$-conductivity

Abstract

One-dimensional distributions of net donor impurity density along the direction of current flow in Gunn diodes have been observed by making use of the signal due to the electron-beam-induced conductivity (β-conductivity). It is shown that the resultant voltage signals are able to reveal clearly various types of doping profiles in the active layers of the Gunn diodes. The relation between the features of the signals and the diode characteristics is examined, and it is confirmed that the deterioration of the diodes is due to the asymmetrical doping profile.