AlGaNpnhomo‐ 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 AlGaNpnjunctions was studied. EL peaks associated with near band‐to‐band transition in AlGaN were detected. The minimum wavelength of EL peak of ∼348 nm (h&ngr;∼3.56 eV, 300 K) was measured for ap‐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. ©1995 American Institute of Physics.