Semiconductor devices useful as light emitting diodes or power transistors are provided. The devices produced by depositing a Zn—O-based layer comprising nanostructures on a Si-based substrate, with or without a metal catalyst layer deposited therebetween. Furthermore, a pair of adjacent p-n junction forming layers is deposited on the ZnO-based layer, where one of the pair is an n-type epitaxial layer, and the other is a p-type epitaxial layer. One or more epitaxial layers may, optionally, be deposited between the ZnO-based layer and the pair of adjacent p-n junction forming layers.