Effect of material properties on low-energy electron transmission in thin chemical-vapor deposited diamond films J. Appl. Phys. 97, 093717 (2005); 10.1063/1.1893212 Improved pseudomorphic high electron mobility transistor structures on InGaAs substratesWe have investigated the effects of various buffer layers on the structural and electronic properties of n-doped InSb films. We find a significant decrease in room-temperature electron mobility of InSb films grown on low-misfit GaSb buffers, and a significant increase in room-temperature electron mobility of InSb films grown on high-misfit InAlSb or step-graded GaSb+ InAlSb buffers, in comparison with those grown directly on GaAs. Plan-view transmission electron microscopy ͑TEM͒ indicates a significant increase in threading dislocation density for InSb films grown on the low-misfit buffers, and a significant decrease in threading dislocation density for InSb films grown on high-misfit or step-graded buffers, in comparison with those grown directly on GaAs. Cross-sectional TEM reveals the role of the film/buffer interfaces in the nucleation ͑filtering͒ of threading dislocations for the low-misfit ͑high-misfit and step-graded͒ buffers. A quantitative analysis of electron mobility and carrier-concentration dependence on threading dislocation density suggests that electron scattering from the lattice dilation associated with threading dislocations has a stronger effect on electron mobility than electron scattering from the depletion potential surrounding the dislocations. Furthermore, while lattice dilation is the predominant mobility-limiting factor in these n-doped InSb films, ionized impurity scattering associated with dopants also plays a role in limiting the electron mobility.

We have investigated the nucleation, growth and transformation of nitride nanostructures synthesized by nitrogen ion implantation into GaAs, followed by thermal annealing. High energy implantation into GaAs thin films results in the formation of a nitrogen-rich amorphous layer, with crystalline remnants. Subsequent annealing leads to the formation of polycrystalline zincblende and/or wurtzite GaN nanocrystals. We discuss the role of annealing time and temperature on nanocrystal nucleation and growth and present a time-temperature-transformation diagram that describes the nucleation of zincblende GaN and its subsequent transformation to wurtzite GaN.