AlGaN pn junctions

AlGaN pn homo- and heterojunctions were fabricated on silicon carbide substrates by metalorganic chemical vapor deposition. AlN concentration in AlGaN layers ranged from 2 to 8 mol %. Mesa structures were made by reactive ion etching. Electroluminescence (EL) from AlGaN pn junctions was studied. EL peaks associated with near band-to-band transition in AlGaN were detected. The minimum wavelength of EL peak of ∼348 nm (hν∼3.56 eV, 300 K) was measured for a p-Al0.08GaN0.92/n-Al0.06Ga0.94N heterojunction. The dependence of the photon energy of the edge EL peak on AlN concentration in AlGaN was measured.