Enhanced Electrical Stability of LP-MOCVD-Deposited ZnO:B Layers by Means of Plasma Etching Treatment

Electrical properties of transparent conductive ZnO:B films, obtained by the low-pressure metal organic chemical vapor deposition (LP-MOCVD) technique, were monitored during the given time, and a heavy worsening of these properties was observed. At the same time, other ZnO:B samples subjected to a post-deposition treatment by argon plasma etching showed an appreciable enhancement of the electrical stability in the given time. A degradation mechanism, involving formation of O- adsorbate and its diffusion inside the grain boundary, is proposed as responsible of the carrier mobility worsening. Furthermore, the beneficial effect of the plasma treatment is explained in terms of a rearrangement of the grain boundary with a decrease of positively charged defect density and, consequently, a slowing down of O- formation rate. Finally, argon plasma post-deposition treatment is proposed as an effective process for obtaining ZnO:B films with an appreciable electrical stability in the given time.