Optimization of Activation Annealing Condition for Boron‐Implanted Diamond

Impurity activation of dopants implanted in diamond is one of the crucial issues for device application of diamond. Boron impurity atoms are introduced in diamond, which expectedly act as acceptors, by ion implantation technique, and are investigated the optimum annealing time for the effective dopant activation. The impurity doping is performed by boron ion implantation at multiple incident energies to obtain a uniform dopant concentration from the surface to 350 nm depth followed by activation annealing at 1300 °C for 5–240 min. The electrical properties of specific resistance, carrier concentration, and conduction type are analyzed as a function of temperature from room temperature to 873 K. The estimated ionization energy is strongly dependent on the annealing time and asymptotically approaches to 0.3 eV, which is theoretically expected ionization energy of acceptor boron, with increasing annealing time. A shorter annealing time ( ≲ 120 min ) $\leq 120 \text{min} \left.\right)$ does not sufficiently recover radiation damages caused by ion implantation forming deep levels, which act as irregular conduction. It is consequently found that an optimum window of annealing time for effective dopant activation and suggested carrier transport mechanisms depending on the annealing time.