Temperature dependence of 248 nm cathodoluminescence band from heavily boron-doped diamond films epitaxially grown on platinum

We have found that heavily (>10(20) cm(-3)) boron-doped diamond films epita xially grown on single-crystal platinum (111) showed a 248 nm cathodolumine scence (CL) band, while emissions due to free exciton (235 nm) and neutral boron bound exciton (238 nm) were absent. In the present study, the tempera ture dependence of the 248 nm band is investigated between 88 K and 300 K. It is found that the peak intensity of the 248 nm band increases by a facto r of 1.4 with a temperature increase from 88 K to 200 K and then saturates at higher temperatures. This result is in strong contrast to the CL intensi ties of both the free exciton and the bound exciton, which decrease signifi cantly with temperature. It is concluded that a new electronic band due to heavily doped boron is the origin of the 248 nm emission.