Formation energies and vibrational frequencies for H in wurtzite GaN were calculated from density fictional theory and used to predict equilibrium state occupancies and solid solubilities for p-type, intrinsic, and n-type material. The volubility of deuterium (D) was measured at 600-800°C as a fhnction of D2 pressure and doping and compared with theory. Agreement was obtained by reducing the H formation energies 0.2 eV from ab-initio theoretical values. The predicted stretch-mode frequency for H bound to the Mg acceptor lies 5'XO above an observed infrared absorption attributed to this complex. It is concluded that currently recognized H states and physical processes account for the equilibrium behavior of H examined in this work.

The band gap of AlxGa1−xN is measured for the composition range 0⩽x<0.45; the resulting bowing parameter, b=+0.69 eV, is compared to 20 previous works. A correlation is found between the measured band gaps and the methods used for epitaxial growth of the AlxGa1−xN: directly nucleated or buffered growths of AlxGa1−xN initiated on sapphire at temperatures T>800 °C usually lead to stronger apparent bowing (b>+1.3 eV); while growths initiated using low-temperature buffers on sapphire, followed by high-temperature growth, lead to weaker bowing (b<+1.3 eV). Extant data suggest that the intrinsic band-gap bowing parameter for AlGaN alloys is b=+0.62(±0.45) eV.

We demonstrate that the insertion of low-temperature (LT) AIGaN interlayers is effective in reducing mismatch-induced tensile stress and suppressing the formation of cracks during growth of AIGaN dkectly upon GaN epilayers., Stress evolution and relaxation is monitored using an in-situ optical stress sensor.

Cavity microstructures formed in Si after ion implantation of He and annealing at 700°C or above are examined with cross-section transmission electron microscopy. A threshold concentration of 1.6 at.% He is identified to form cavities that survive such anneals. The cavities coarsen with a constant volume of 15 nm3/nm2 (per wafer surface area), corresponding to -0.75 lattice sites per implanted He atom. The internal area of the cavities is 3-7 times that of the wafer surface area for fluences of lx1017 He/cm2.Transition metal atoms (Cu, Ni, Coy Fe, Au) are shown to be strongly trapped (1.5 -2.2 eV) on the cavity walls by chemisorption. Whereas Cu, Au and Ni are bound more strongly to the cavity sites than to their respective precipitated phases, Co and Fe are more strongly bound to their silicides; nonetheless, appreciable trapping of Co and Fe does occur in equilibrium with the silicides. Cavity trapping appears to be an effective gettering mechanism at low impurity levels, as needed to meet future microelectronics device requirements.

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