Observation of a negative electron affinity for heteroepitaxial AlN on α(6H)-SiC(0001)
Contributors: M.C. Benjamin, Cheng Wan, R.F. Davis, and Robert J. Nemanich
ABSTRACT
This study demonstrates the presence of a negative electron affinity (NEA) surface on AlN was grown on α(6H)‐SiC. Heteroepitaxial AlN was grown on α(6H)‐SiC(0001) substrates by molecular beam epitaxy techniques. The surface electronic states were characterized by ultraviolet photoemission obtained at surface normal. The observation of a sharp spectral feature at the lowest energy of the emitted electrons is an indication of a surface with a negative electron affinity. In addition, the trend of the NEA feature was examined as a function of annealing. The surface Fermi level is found to be near the middle of the AlN gap, and a possible band alignment between the AlN and SiC is presented.