Temperature dependence of the Raman shift in GaAs conformal layers grown by hydride vapor phase epitaxy

Abstract

Raman spectra between room temperature and 350 °C were measured in GaAs layers grown by hydride vapor phase epitaxy on Si substrates using the selective conformal growth method. The contributions of the thermal expansion, anharmonic phonon decay, and strain are considered in order to analyze the Raman data. The tensile strain in the conventional GaAs/Si seed and in the conformal GaAs layers was determined from the Raman spectra. It is shown that the thin SiO2 layer between the GaAs and the Si substrate is a compliant layer that plays an important role in the reduction of the dislocation density in the conformal layers. The tensile strain in conformal layers was higher than in the conventional GaAs/Si layers, in which strain is relieved by the high density of dislocations.

Observing visible-range photoluminescence in GaAs nanowires modified by laser irradiation

“…S2 in the supplementary material) allows to estimate the temperature of the nanowires. 31 For power density of 1.4 MW/cm 2 , the nanowire temperature reaches ~ 700 K, that is enough to evaporate the arsenic layer from the nanowire surface.…”

Supercontinuum generation from 2 to 20 μm in GaAs pumped by picosecond CO_2 laser pulses

“…2 has a bandwidth of 135 THz, from 2 to 20 μm, and is limited by the transmission of the material [14]. The spectrum contains a feature related to the 8.55 THz Raman shift in GaAs [15], which results in a Stokes peak near 16 μm. Harmonic generation results in features at 5.3 and 3.5 μm.…”

Strain and anisotropy effects studied in InAs/GaAs(2 2 1) quantum dashes by Raman spectroscopy

“…The LO modes are shifted about 4 cm -1 , while the TO modes are 1.7 cm -1 . As it is known the Raman peak shifts are linear with the stress σ, [30][31][32] i.e. Δω=aσ and Δω=bσ for the LO-and TO-mode, respectively.…”