Electroluminescence of ZnO-based semiconductor heterostructures

Using pulsed laser deposition, we have grown n-ZnO/p-GaN, n-ZnO/i-ZnO/p-GaN and n-ZnO/n-Mg_0.2Zn_0.8O/i-Cd_0.2Zn_0.8O/p-GaN light-emitting diode (LED) heterostructures with peak emission wavelengths of 495, 382 and 465 nm and threshold current densities (used in electroluminescence measurements) of 1.35, 2, and 0.48 A cm^-2, respectively. Because of the spatial carrier confinement, the n-ZnO/n-Mg_0.2Zn_0.8O/i-Cd_0.2Zn_0.8O/p-GaN double heterostructure LED offers a higher electroluminescence intensity and lower electroluminescence threshold in comparison with the n-ZnO/p-GaN and n-ZnO/i-ZnO/p-GaN LEDs.