A5. The negative electrical layer at the boundary of a p-n junction is formed by __ 1. negative ions of donor atoms 2. holes 3. electrons A. negative ions of acceptor atoms

The correct answer is 3. electrons.<br /><br />In a p-n junction, the negative electrical layer, also known as the depletion region, is formed by the accumulation of electrons in the n-type material and the absence of electrons in the p-type material. The electrons in the n-type material are attracted to the positive charge created by the absence of electrons in the p-type material, forming a region devoid of free charge carriers, which is the depletion region.