Bidirectional Direct-Current Electroluminescence From I-Mgxzn1-Xo/N-Zno/Siox Double-Barrier Heterostructures On Si

We report bidirectional direct-current electroluminescence (EL) from i-MgxZn1-xO/n-ZnO/SiOx double-barrier heterostructures on Si. When the heterostructure-based device is forward biased with negative voltage applied on Si, ultraviolet (UV) emission is more intense than visible emissions. The visible emissions appear only at sufficiently high currents. As the device is reverse biased, the visible emissions dominate the EL at low currents. However, they are gradually overridden by the UV emission with increasing current. The EL mechanism has been discussed in terms of energy band structures of the device under forward and reverse biases.