There is provided a process for etching a semiconductor material, comprising the steps of: providing an electrochemical cell containing an etching electrolyte, the etching electrolyte being selected from the group of acidic electrolyte solutions, alkaline solutions, neutral solutions, and molten electrolytes; immersing the semiconductor material in the etching electrolyte, whereby at least one surface of the semiconductor material contacts the etching electrolyte; thereafter negatively biasing the semiconductor material; and while continuing to negatively bias the semiconductor material, illuminating at least part of the at least one surface of the semiconductor material which contacts the etching electrolyte with light selected from the group of ultraviolet, visible, and infrared light. There is also provided an apparatus for effecting the process of the invention, as well as semiconductor materials so etched.