ABSTRACT
Mixed-anion nitrides exhibit a duality in their electronic and transport properties, showing both homogeneous (bulklike) and heterogeneous (fluctuating) behavior. One observes homogeneous, bulklike characteristics, such as resonances within the continua, rigid shift of the conduction band with temperature and pressure, the appearance of new bulklike absorption edge such as E+, and a split El. Significantly, the popular "band anticrossing" (BAC) model of Shan et al. [1] only addresses this homogeneous behavior. On the other hand, one also notes characteristics of heterogeneous localization centers and alloy fluctuations, such as a distribution of various nitrogen pairs and clusters whose levels are within the forbidden energy gap, absorption vs. emission Stokes shifts, emission blueshift upon increased excitation power, band tails with long decay times, and asymmetric line shapes. These heterogeneous localization characteristics are particularly apparent in photoluminescence (vs. absorption) and are pertinent to the design of photoemitting devices such as LEDs and lasers.
