Annealing-induced evolution of boron-doped polycrystalline diamond

Diamond shows great promise for opening up new paradigms in the semiconductor industry and quantum electronics. Here, we investigate the influence of thermal annealing on the structural and electrical transport properties of heavily boron-doped polycrystalline diamond (BPD) thin films. Our structural analyses show that annealing beyond 600 ◦C can induce severe local amorphization in a BPD thin film and transform it into a binary mixture of spatially separate domains of amorphous carbon (a-C) and diamond grains. Due to this annealing-induced morphology and phase segregation, the BPD thin films demonstrate a significant decrease of the electron localization radius and a distinct increase of the Ginzburg-Landau coherence length. Our research provides physical insight into the conversion of diamond to a-C and aids in defining the application scope of BPD by revealing its heat tolerance.