MOCVD growth and electrical studies of p-type AlGaN with Al fraction 0.35

We present a study on the high performance p-type AlxGa1−x  N (x=0.35x=0.35) layers grown by low-pressure metalorganic chemical vapor deposition on AlN template/sapphire substrate. The influence of growth conditions on the p-type conductivity of the AlxGa1−x  N (x=0.35x=0.35) alloy is investigated. From the Hall effect and I–V transmission line model measurements, a p-type resistivity of 3.5 Ω cm for AlxGa1−x  N (x=0.35x=0.35) epilayers are achieved. To the best of our knowledge, this is the lowest resistivity ever measured for the uniform p-type AlGaN with Al fraction higher than 0.3. The Mg and impurities (O, C and H) of the atom concentration in the epi-layers are analyzed by means of SIMS depth profiles, which reveal the dependence of impurities incorporation on the III elements and growth temperature.