We propose experimental and theoretical investigations of light generated electrons and holes in GaN-based ternary and quaternary materials and devices, including compounds with band gap in UV range.
We will use Light-Induced Transient Gratings (LITG) system, which exploits nondestructive techniques including the quasi-steady-state and time-resolved photoluminescence spectroscopy in the temperature range from 8 K to 600 K under laser excitation at different wavelengths.
Our studies will include studies of luminescence at different temperatures, excitation intensities and wavelengths, time-resolved luminescence, investigations of stimulated emission, and LITG measurements. This will allow us to determine carrier densities, lifetimes, diffusion coefficients, and surface recombination rates (mapping large area wafers) throughout the visible range into UV.
Comparison of results obtained by the new technique based on LITG with the results of the conventional luminescence spectroscopy will provide a new insight into the problems, which are of the primary importance for exploitation of the wide-band-gap nitrides in light emitting and detecting devices.
Physics of nitride-based wide band gap semiconductors is dramatically different in many key areas from that of more conventional semiconductors, such as silicon or GaAs. This is linked to a different (and more complex) symmetry that allows for spontaneous polarization. Determining basic semiconductor parameters for nitrides and relating them to the materials growth and fabrication process, where appropriate, is crucial for developing new wide band semiconductor science and for supporting industry with applications ranging from solid state lighting to ultra high power radars, from water purification to biological hazard detection.
