According to an example embodiment, an electrical energy generator includes at least one piezoelectric structure, a semiconductor layer and a contact layer. The at least one piezoelectric structure includes a material having piezoelectric characteristics. One surface of each piezoelectric structure forms a p-n junction with the semiconductor layer. The other end of each piezoelectric structure contacts the contact layer that is formed of a material having metal-insulator transition (MIT) characteristics. The piezoelectric structure may be an elongated member, such as a nanowire.