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

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 reveals that RhP2 adopts a monoclinic structure with the cell parameters a = 5.7347(10) & Aring;, b = 5.7804(11) & Aring;, and c = 5.8222(11) & Aring;, space group P2(1)/c (No. 14). The electrical resistivity rho(T) measurements indicate that RhP2 exhibits narrow-bandgap behavior with the activation energies of 223.1 meV and 27.4 meV for two distinct regions, respectively. The temperature-dependent Hall effect measurements show electron domain transport behavior with a low charge carrier concentration. We find that RhP2 has a high mobility mu(e) similar to 210 cm(2)& sdot;V-1 & sdot;s(-1) with carrier concentrations n(e) similar to 3.3 x 10(18) cm(-3) at 300 K with a narrow-bandgap feature. The high mobility mu(e) reaches the maximum of approximately 340 cm(2)& sdot;V-1 & sdot;s(-1) with carrier concentrations n(e) similar to 2 x 10(18) cm(-3) at 100 K. No magnetic phase transitions are observed from the susceptibility chi(T) and specific heat C-p(T) measurements of RhP2. Our results not only provide 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.