Photoconductivity of Ge crystals with pure surface

For the first time photoconductivity of Ge crystals with pure surfaces, prepared using shearing in liquid helium, is investigated. Considerable photoconductivity increase of such crystals in the proper light absorption area is observed.It is found that after surface oxidation redundant conductivity becomes zero. The effect observed is explained by formation of a conducting channel near the pure Ge surface due to electron capture on broken bonds