Unification of the Band Anticrossing and Cluster-State Models of Dilute Nitride Semiconductor Alloys

We show that a quantitative description of the conduction band in Ga(In)NAs is obtained by combining the experimentally motivated band anticrossing model with detailed calculations of nitrogen cluster states. The unexpectedly large electron effective mass values observed in many GaNAs samples are due to hybridization between the conduction band edge $E_{-}$ and nitrogen cluster states close to the band edge. Similar effects explain the difficulty in observing the higher-lying $E_{+}$ level at low N composition. We predict a decrease of effective mass with hydrostatic pressure in many GaNAs samples.