We present a comprehensive and up-to-date compilation of band parameters for all of the nitrogen-containing III–V semiconductors that have been investigated to date. The two main classes are: (1) “conventional” nitrides (wurtzite and zinc-blende GaN, InN, and AlN, along with their alloys) and (2) “dilute” nitrides (zinc-blende ternaries and quaternaries in which a relatively small fraction of N is added to a host III–V material, e.g., GaAsN and GaInAsN). As in our more general review of III–V semiconductor band parameters [I. Vurgaftman et al., J. Appl. Phys. 89, 5815 (2001)], complete and consistent parameter sets are recommended on the basis of a thorough and critical review of the existing literature. We tabulate the direct and indirect energy gaps, spin-orbit and crystal-field splittings, alloy bowing parameters, electron and hole effective masses, deformation potentials, elastic constants, piezoelectric and spontaneous polarization coefficients, as well as heterostructure band offsets. Temperature an...

Band parameters for nitrogen-containing semiconductors

Reflection anisotropy spectroscopy (RAS) is a non-destructive optical probe of surfaces that is capable of operation within a wide range of environments. In this review we trace the development of RAS from its origins in the 1980s as a probe of semiconductor surfaces and semiconductor growth through to the present where it is emerging as a powerful addition to the wide range of existing ultra-high vacuum (UHV) surface science techniques. The principles, instrumentation and theoretical considerations of RAS are discussed. The recent progress in the application of RAS to investigate phenomena at metal surfaces is reviewed, and applications in fields including electrochemistry, molecular assembly, liquid crystal device fabrication and remote stress sensing are discussed. We show that the experimental study of relatively simple surfaces combined with continuing progress in the theoretical description of surface optics promises to unlock the full potential of RAS. This provides a firm foundation for the application of the technique to the challenging fields of ambient, high pressure and liquid environments. It is in these environments that RAS has a clear advantage over UHV-based probes for investigating surface phenomena, and its surface sensitivity, ability to monitor macroscopic areas and rapidity of response make it an ideal complement to scanning probe techniques which can also operate in such environments.

http://iopscience.iop.org/article/10.1088/0034-4885/68/6/R01/pdf

Reflection anisotropy spectroscopy

The band gap of AlxGa1−xN is measured for the composition range 0⩽x 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.

The band-gap bowing of AlxGa1−xN alloys

We present quantitative calculations of the electron drift mobility in wurtzite (WZ) and zincblende (ZB) structure n-type AlGaN/GaN modulation-doped field-effect transistors. The two-dimensional character of the quantum confined carriers as well as spontaneous and piezoelectric electric field effects are fully taken into account. For given doping concentration, we find that the internal electric fields lead to a much stronger carrier confinement and higher channel densities than in standard III–V materials. For high quality n-type heterostructures, we predict a room temperature mobility at high densities close to 2000 cm2/V s.

Mobility of two-dimensional electrons in AlGaN/GaN modulation-doped field-effect transistors

A preceding companion paper provides a general introduction to Variable Angle Spectroscopic Ellipsometry (VASE), and also describes many typical applications of the technique. In this paper, more advanced VASE applications are discussed. These applications rely on recent advances in ellipsometric hardware, which allow extremely accurate ellipsometric data to be acquired over a broad spectral range, from the IR to VUV. This instrumentation can also quantitatively measure the optical response of nonisotropic samples. Advanced data analysis techniques are also presented.

M. Cardona

Papers

Spectroscopic ellipsometry measurements of AlxGa1−xN in the energy range 3–25 eV