P‑Type Spin-Coated Sol-Gel CrO Layer by Postannealing in Vacuum.

The hole carriers of spin-coated sol-gel CrO could be activated successfully by postannealing at a temperature of more than 500 °C in a vacuum without doping. The sheet hole concentration increased with the increase in the postannealing temperature and could reach 5 × 10 cm at a postannealing temperature of 680 °C. However, activating the hole carriers for annealing CrO in N ambient at a low pressure of 3 mTorr and a temperature of 560 °C or higher was difficult. The N-annealed CrO could regain the same electrical properties as vacuum-annealed CrO by annealing under vacuum again. A comparison of the deconvoluted XPS spectra of the postannealed CrO in a vacuum and in N ambient showed that the amount of Cr, Cr, Cr, Cr, and O vacancies was strongly correlated with the hole carrier creation of CrO.