Investigation of Compositional Disorder in GaAsN:H

Proceedings della 28ma "International Conference on the Physics of Semiconductors", Vienna, Austria (2006)

Carrier relaxation dynamics in annealed and hydrogenated (GaIn)(NAs) quantum wells

We measured time-resolved photoluminescence on as-grown, annealed, as well as annealed and hydrogenated (Ga0.7In0.3)(N0.006As0.994)∕GaAs quantum-well structures. The postgrowth treatment changes not only the photoluminescence decay time but also the intensity of photoluminescence directly after excitation. This initial luminescence intensity is determined by a competition between relaxation of electrons into nitrogen related potential fluctuations in the conduction band and their capture by deep traps. In contrast, the decay of the photoluminescence is mainly determined by the competition between radiative and nonradiative recombination, which are both influenced by localization. Annealing decreases localization effects and nonradiative recombination. Hydrogenation also reduces localization effects but increases nonradiative recombination

Correlation of band formation and local vibrational mode structure in Ga(0.95)Al(0.05)As(1-x)N(x) with 0<= x <= 0.03

We present comprehensive optical studies of a series of as-grown and hydrogenated Ga(0.95)Al(0.05)As(1-x)N(x) epitaxial layers with various amounts x of substitutional nitrogen. Photomodulated and contactless electromodulated spectroscopies were performed to gain information about the influence of N incorporation on the band structure. The results are interpreted in terms of the band-anticrossing model and compared to corresponding GaAs:N data. The local vibrational properties of the N atoms studied by Raman and Fourier-transform infrared absorption were found to depend strongly on the Ga/Al nearest-neighbour configurations of N. Correlations between local N environments and global band structure properties are confirmed by comparing results obtained before and after hydrogenation of the samples

Influence of N-cluster states on the gyromagnetic factor of electrons in GaAs(1-x)N(x)

The effective gyromagnetic factor of electrons, ge*, has been determined by Zeeman splitting measurements in a large number of Ga As1-x Nx GaAs (x<0.7%) samples. Upon N incorporation, ge* shows first a sign reversal with respect to that of GaAs, then increases abruptly for a nitrogen concentration of order of 0.04%, and finally displays a nonmonotonic dependence on composition for higher x values. This behavior is well reproduced by a modified kp model taking into account a nonmonotonic loss of \u393 character of the conduction band minimum due to multiple crossings between the redshifting conduction band edge and N -cluster states

Interaction between conduction band edge and nitrogen states probed by carrier effective-mass measurements in GaAs(1-x)N(x)

The electron effective mass, me, has been determined by magnetophotoluminescence in as-grown and hydrogenated Ga As1-x Nx samples for a wide range of nitrogen concentrations (from x<0.01% to x=1.78%). A modified kp model, which takes into account hybridization effects between N cluster states and the conduction band edge, reproduces quantitatively the experimental me values up to x 640.6%. Experimental and theoretical evidence is provided for the N complexes responsible for the nonmonotonic and initially puzzling compositional dependence of the electron mass