Deep Ultraviolet Light Emitting Diodes Based on Short Period Superlattices of AlN/AlGa(In)N

Abstract

We report a systematic study of the optical properties of superlattices of AlN/Al0.08Ga0.92(In)N with periods in the range of 1.25-2.25 nm. The superlattices were grown on sapphire substrates using gas source molecular beam epitaxy with ammonia. Effective bandgaps between 4.5eV (276 nm) and 5.3eV (234 nm), as determined by optical reflectivity measurements, were obtained by adjusting the barrier and well thickness. These superlattices can be doped n- and p-type. We demonstrate double heterostructure light emitting diodes operating at wavelengths as short as 262 ± 2 nm.