  We report on S-doping of ZnSb for S concentrations ranging from 0.02 at% to
2.5 at%. There are no previous reports on S-doping. ZnSb is a thermoelectric
material with some advantages for the temperature range 400 K - 600 K. The
solid solubility of S in ZnSb was estimated to be lower than 0.1% from
observations of precipitates by scanning microscopy. Hall and Seebeck
measurements were performed as a function of temperature from 6K to 623 K. The
temperature dependence of the electrical properties suggests that S introduces
neutral scattering centers for holes in the p-type material. An increase in
hole concentration by S is argued by defect reactions involving Zn vacancies.
