Abstract
Photoelectrochemical properties of high purity 
and 
were investigated. Photocurrent efficiencies were measured in various electrolytes and found to depend on the electrolyte used. Direct measurement of spectrophotometric absorption coefficients showed them to be significantly higher than those deduced from i‐V curves indicating that only a fraction of the light absorbed resulted in electrochemically reactive holes. When the lower absorption coefficients were employed the current‐potential curves could be fit within ±1% to the depletion layer theory of Gärtner.