Incomplete Solubility in Nitride Alloys

摘要: A model based on the valence-force-field (VFF) has been developed specifically for calculation of irascibility gaps in III-V nitride alloys. In dilute limit, this allows relaxation atoms both sublattices. It was found that energy due to bond stretching and bending lowered solubility limit increased substantially when sublattices were allowed relax distances as large sixth nearest neighbor positions. Using model, equilibrium mole fraction N GaP calculated be 6×l0−7 at 700°C. This is slightly higher than results from semi-empirical delta lattice parameter (DLP) model. Both temperature dependence absolute values agree closely with experimental data. The more three orders magnitude larger result obtained using VFF group V atom positions given by virtual crystal approximation, i.e., only first bonds. Other systems, such GaAsN, AlPN, AlAsN, InPN, InAsN investigated well. fractions nitrogen InP InAs are highest, which agrees well recent data where high concentrations have produced Calculations also performed alloy systems mixing III sublattice so important device applications. Allowing 3rd gives an GaN 800°C less 6%. Again, agreement DLP calculation. may partially explain difficulties experienced growth these Indeed, evidence solid immiscibility recently reported. significant miscibility gap AlInN system, but AlGaN system completely miscible.