n-TYPE DOPING OF DIAMOND BY ION-IMPLANTED GROUP VI ATOMS

摘要

Nitrogen forms deep donor centers at≈1.7 eV below the conduction band of diamond. Recently, phosphorus donors have been activated in diamond. Although shallower, they still have an ionization energy E_D≈0.6 eV. In this study, it is demonstrated that shallower donors can be activated in diamond by means of the cold-implantation-rapid-annealing (CIRA) routine, when using either oxygen or sulfur ions. The key is to employ a relatively low temperature for the rapid annealing step. One reason for this requirement is diamond's negative electron affinity (NEA). The conduction band is situated at≈0.5 eV above the vacuum level. This indicates that shallow donor centers (with E_D < 0.5 eV) will be high energy (metastable) states. Such states, if they can be created, should tend to relax into deeper lying states at high annealing temperatures. Low annealing temperatures are thus needed to "quench" them into these higher energy configurations.