Thermopower measurements on arsenic from 2 to 300 K

$S_{11}$ and $S_{33}$ thermopower components of arsenic have been determined in the temperature range 2-300 K. The data on trigonal ($S_{33}$) samples are the first reported investigations below 80 K. The measurements were made on high-quality melt-grown single crystals with resistivity ratios in excess of $3500\left(S_{11}\right)$ and $5300\left(S_{33}\right)$, the largest reported to date. While the thermopower $S_{11}$ is positive above 15 K, the $S_{33}$ component is negative throughout the investigated temperature range. Above 70 K, both $S_{11}$ and $S_{33}$ thermopowers are purely of diffusion origin. At lower temperatures the thermopowers show pronounced anomalies associated with phonon drag of electrons and holes. With increasing sample perfection both $S_{11}$ and $S_{33}$ tend to become less negative.