Single Crystal Growth and Transport Properties of Narrow Band Gap Semiconductor RhP2

Here, we report the growth of high-quality single crystals of RhP2, and systematically study its structure and physical properties by transport, magnetism, and heat capacity measurements. Single-crystal X-ray diffraction revealed RhP2 adopts a monoclinic structure with the cell parameters a=5.7347(10) Å, b=5.7804(11) Å, and c=5.8222(11) Å, space group P21/c (No. 14). The electrical resistivity ρ(T) measurements indicate that RhP2 exhibits a narrow band gap behavior with the activation energies of 223.1 m eV and 27.4 m eV for two distinct regions, respectively. The temperature-dependent Hall effect measurements show electron domain transport behavior with a low charge carrier concentration. We found that RhP2 has a high mobility μe~210 cm2v-1s-1 with carrier concentrations ne~3.3×1018 cm-3 at 300 K with a narrow band gap feature. The high mobility μe reached a maximum of approximately 340 cm2v-1s-1 with carrier concentrations ne~2×1018 cm-3 at 100 K. No magnetic phase transitions were observed from the susceptibility χ(T) and specific heat Cp(T) measurements of RhP2. Our results not only offer effective potential as a material platform for studying exotic physical properties and electron band structures but also motivate further exploration of their potential photovoltaic and optoelectronic applications.