Bidirectional photocurrent of holes in layers of Ge/Si quantum dots

Spectra of the photocurrent of holes in $\delta$-doped Si layers with Ge quantum dots in weak external electric fields have been studied. It has been established that the photocurrent of the holes in the photovoltaic mode changes its sign with the increase in the impurity concentration in the $\delta$ layers. It has been found that there is a voltage range in the vicinity of the zero bias in which the direction of the photocurrent is determined by the wavelength of the exciting radiation.