Radiative-Recombination Thermodynamics in Boron-Doped Diamond

Boron-doped diamond is a wide-bandgap semiconductor with excellent semiconductor properties, which is widely utilized in various applications. Till now, the thermodynamic rules governing the carrier transitions in this material have not been fully understood. In this research, the different luminescence behaviors of boron-doped diamond under 193 nm pulse laser with high- and low- power density excitation are analyzed. Under high-power density excitation (@approximate to 63 kW cm-2), the emission intensity of excitons is nearly ten times higher than that of defect luminescence. Conversely, under low-power density excitation (@approximate to 1.4 kW cm-2, different emission peaks exhibit similar intensities, indicating a competitive relationship among them. Based on experimental and theoretical analyses, the difference is attributed to the thermodynamic distribution of carriers at varying excitation powers. Specifically, high excitation power brings an independent behavior of each emission peak, and the exciton emission is described by a phonon-assisted radiation model; different from that, the competition among different emission centers under the condition of low excitation power cannot be neglected, and now the thermodynamic evolution of each emission peak is described by a carrier trapping-dissociation model. Thermodynamic rules governing carrier transitions in boron-doped diamond have not been fully understood. Here, it is suggested that the thermodynamic distribution of carriers under 193 nm excitation with varying powers lead to the luminescence differences in boron-doped diamond, especially under low-power excitation, the consideration of competition among different emission centers is necessary. image