A semiconductor light emitting device including a substrate, an electrode and a light emitting region is provided. The user device is configured to determine an amount of power used by the display screen; determine power usage information that identifies a portion of the amount of power that is attributable to the application based on the application being initiated during the time period; and store the power usage information. A structure is provided in which the N- or C-doped Si layer has approximately the same diffusion rate for a p-type dopant as the overlying SiGe channel layer. Selection circuitry is operable to select the two-terminal nanotube switching device for read and write operations. An external field such as electric field or magnetic field may be applied to the amorphous material, or a seed crystal or crystalline substrate may be used to promote crystallization from a contact interface between the amorphous material and the seed crystal or crystalline substrate.