Abstract
The hole carriers of spin-coated sol-gel Cr(2)O(3) 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(14) cm(-2) at a postannealing temperature of 680 °C. However, activating the hole carriers for annealing Cr(2)O(3) in N(2) ambient at a low pressure of 3 mTorr and a temperature of 560 °C or higher was difficult. The N(2)-annealed Cr(2)O(3) could regain the same electrical properties as vacuum-annealed Cr(2)O(3) by annealing under vacuum again. A comparison of the deconvoluted XPS spectra of the postannealed Cr(2)O(3) in a vacuum and in N(2) ambient showed that the amount of Cr(2+), Cr(4+), Cr(5+), Cr(6+), and O vacancies was strongly correlated with the hole carrier creation of Cr(2)O(3).