Temperature-Dependent Properties of Nearly Ideal ZnO Schottky Diodes

The current-voltage characteristics of low-ideality-factor (1.09 at 300 K) ZnO Schottky diodes were investigated over the temperature range of 40-423 K. Planar geometry devices were fabricated on the Zn-polar face of a low carrier concentration (n = 1 x 10(14) cm(-3)) hydrothermally grown bulk ZnO single crystal wafer. The current transport was dominated by thermionic emission between 293 and 423 K, provided the ZnO surface was exposed to air. The nearly ideal characteristics of the diodes yielded an experimental Richardson constant of 10 +/- 6 A . cm(-2) . K-2, close to the theoretical value of 32 A . cm(-2) . K-2, and two orders of magnitude larger than previously reported values.