Ultraviolet and violet GaN light emitting diodes on silicon

We report the fabrication and characterization of GaN-based double heterostructure light emitting diodes grown by molecular beam epitaxy on Si(111) substrates. Light emitting diode operation is achieved by using the conducting Si(111) substrate as a backside n contact and a standard transparent Ni/Au p contact. We observe electroluminescence peaked in the ultraviolet $\text{∼360\hspace{0.17em}}\mathrm{nm},$ with a full width at half maximum of $\text{∼17\hspace{0.17em}}\mathrm{nm}$ and in the violet at ∼420 nm. Electron microscopy studies indicate a high density of threading and planar defects. Consequences of these are discussed.