Application of electron holography to the determination of contact potential difference in an AlGaN/AlN/Si heterostructure.

Electron holography was applied to determine the contact potential differences in an AlGaN/AlN/Si heterostructure formed by metallorganic vapor phase epitaxy. Since mean inner potentials are generally different for different materials, their values before and after forming the junction were evaluated first, then the contact potential difference was obtained by subtracting the difference of the mean inner potentials before forming the junction from the corresponding difference after forming the junction. The contact potential differences thus obtained were consistent with a reported asymmetric nonlinear behavior in the current-voltage characteristics measured for a similar heterojunction diode.