Molybdenum carbonitride Schottky contacts prepared by thermal atomic layer deposition on gallium nitride

Electrical contacts to semiconductors are usually prepared by physical vapor deposition, but we explore thermal atomic layer deposition (ALD) to create molybdenum carbonitride-based Schottky diodes to gallium nitride. We also compare our findings to similar diodes that we previously prepared by plasma enhanced atomic layer deposition (PEALD). A stop-flow process was implemented to overcome a nucleation delay on gallium nitride during thermal ALD, which was not required for PEALD; however, the as-deposited diodes had better electrical behavior when prepared by thermal ALD. Current-voltage measurements reveal a higher as-deposited Schottky barrier height of 0.68 ± 0.01 eV and a lower ideality factor of 1.06 ± 0.01 using thermal ALD. After annealing the diodes at 600 °C, the Schottky barrier height increased to 0.82 ± 0.04 eV , and the ideality factor decreased to 1.04 ± 0.04 , which are similar to annealed diodes prepared by PEALD. Although capacitance-voltage measurements indicate a higher barrier height (0.99 ± 0.1 eV) after annealing diodes prepared by thermal ALD, there was a minimal variation as a function of frequency. Together with the abrupt interface between the molybdenum carbonitride and gallium nitride observed by transmission electron microscopy, these measurements indicate a high-quality interface.