Raman scattering study on Ga_1–xMn_x As prepared by Mn ions implantation, deposition and post‐annealing

Abstract

Raman scattering measurements have been performed in Ga 1−x Mn x As crystals prepared by Mn ions implantation, deposition, and post-annealing. The Raman spectrum measured from the implanted surface of the sample shows some weak phonon modes in addition to GaAs-like phonon modes, where the GaAs-like LO and TO phonons are found to be shifted by approximately 4 and 2 cm -1 , respectively, in the lower frequency direction compared to those observed from the unimplanted surface of the sample. The weak vibrational modes observed are assigned to hausmannite Mn 3 O 4 like. The coupled LO-phonon plasmon mode (CLOPM), and defects and As related vibrational modes caused by Mn ions implantation, deposition, and post-annealing are also observed. The compositional dependence of GaAs-like LO phonon frequency is developed for strained and unstrained conditions and then using the observed LO GaAs peak, the Mn composition is evaluated to be 0.034. Furthermore, by analyzing the intensity of CLOPM and unscreened LO GaAs phonon mode, the hole density is evaluated to be 1.84×1018 cm -3 .

Temperature stable 13 μm emission from GaAs

“…The existence of both TO and LO phonon modes in Mn implanted and annealed sample confirm the Ga 1-x Mn x As alloy formation. [16]. In our case the shift of the LO phonon mode is 2.5 cm −1 which corresponds to 2% of Mn incorporated into GaAs.…”

“…In our case the shift of the LO phonon mode is 2.5 cm −1 which corresponds to 2% of Mn incorporated into GaAs. Moreover the LO phonon mode is strongly asymmetric and can be de-convoluted into the LO phonon mode and coupled-LOphonon plasmon mode (CLOPM) usually optically active in p-type heavily doped binary semiconductors [16]. The position of the CLOPM depends on the carrier concentration and moves from the LO to the TO phonon mode position with increasing hole concentration.…”

Lattice dynamics of Ga1−xMn x N and Ga1−xMn x As by first-principle calculations

“…We can attribute this discrepancy to the fact that Mn induces local distortions in the GaAs lattice [19], giving rise to local modes, which were detected only in ion-implanted sample experiments [9], and it is not predicted by the VCA model. We would like to point out that in the VCA model, no singularity is expected on the TO modes, and then, the TO frequencies shift regularly between the natural frequency in the pure crystal and the impurity frequency [11].…”

“…Besides, in the molecular beam epitaxy grown samples, a local Mn mode vibration was not observed, as observed in the ion-implanted samples [9,10]. For the Ga 1− x Mn x N alloys, it was verified that the A 1 (LO) mode is shifted to higher frequencies, while the E 1 (LO) mode decreases with the increasing Mn content.…”

Origin and enhancement of the 1.3 μm luminescence from GaAs treated by ion-implantation and flash lamp annealing

“…Compared with the standard wavenumber of the LO mode for bulk GaAs, the peaks revealed a -2 cm -1 shift due to lattice shrinkage by N-doping [17,18]. For the Zn-doped p-type GaAs the LO phonon mode of GaAs is almost invisible, while the strongest peak can be attributed to the coupled-LO-phonon-plasmon mode (CLOPM) which is usually optically active in heavily doped p-type semiconductors [19]. According to the influence of hole concentration on the CLOPM peak shift [20], the hole concentration in our Zn-doped GaAs is of the order of 10 19 cm -3 .…”