Papers by Author: D.J. Chen

Abstract: The weak-localization of the two-dimensional electron gas (2DEG) in a modulation-doped Al0.22Ga0.78N/GaN single quantum well has been investigated through the magnetoresistance measurements. The elastic scattering time τε, dephasing time τφ and spin-orbit(s-o) scattering time τso at various temperatures are obtained. The fitting parameters indicate that the inelastic scatterings to the 2DEG are mainly due to the piezoelectric field and the alloy disorder in the AlxGa1-xN barrier. When the second subband in the triangular quantum well at the heterointerface is occupied by the 2DEG, the anti-weak localization is observed clearly, which is due to the strong spin-orbit interaction. The spin-orbit effect dominates the quantum correction of the conductivity in the upper subband. The intersubband scattering becomes stronger with increasing temperature.

Abstract: Infrared reflectivity measurements of GaN1-xPx alloys and quantitative fittings using Lorentz model have been carried out. In the GaN1-xPx alloys, two competitive mechanisms that determine the carrier concentration have been put forward. The one is from the effect of the isoelectronic traps which decrease the carrier concentration while the other is from the effect of defects which increase the carrier concentration. The calculated results of imaginary part of the elastivity of GaN and GaN1-xPx alloys show that the longitudinal optical phonon-plasmon (LPP) modes shift to high frequency direction and its linewidth gradually broadens with increasing carrier concentration in GaN1-xPx, indicating that the coupling of LPP modes gradually enhances and the damping of LPP modes gradually augments.