Local vibrational mode study of carbon-doped $\mathrm{InAs}$

Carbon-doped $\mathrm{InAs}$ samples grown by organometallic vapor phase epitaxy were studied by Raman and IR spectroscopy. Local vibrational modes (LVMs) related to isolated substitutional carbon acceptors, carbon acceptor-hydrogen complexes, and dicarbon centers were detected in samples doped with two isotopes of carbon. The energies of the observed carbon-hydrogen modes are in close agreement with carbon acceptor-hydrogen modes in $\mathrm{GaAs}$ and $\mathrm{InP}$, and are consistent with hydrogen occupying a bond-center position in the complex. No sign of substitutional carbon donors was observed. The $n$-type conductivity of carbon-doped $\mathrm{InAs}$ can be explained by the presence of dicarbon centers that are believed to be deep donors. The stretch mode of this complex was detected at $1832{\mathrm{cm}}^{-1}$ by Raman spectroscopy in as-grown and annealed samples.

Figure 1

RT Raman spectra of samples doped with ${}^{12}\mathrm{C}$ and ${}^{12}\mathrm{C}$ and ${}^{13}\mathrm{C}$.

Figure 2

IR spectra measured at $T=25\mathrm{K}$. The solid line represents the sample doped with both isotopes and the dash-dot line is for the sample doped with ${}^{12}\mathrm{C}$.

Figure 3

The carbonlike $A_1$ mode of carbon-hydrogen complexes for samples doped with ${}^{12}\mathrm{C}$ (dash-dot line) and the one doped with ${}^{12}\mathrm{C}$ and ${}^{13}\mathrm{C}$ (solid line).

Figure 4

Low temperature $(T=20\mathrm{K})$ IR spectra of $\mathrm{InAs}:{}^{12}\mathrm{C}$ and $\mathrm{InAs}:{}^{12}\mathrm{C}$ and ${}^{13}\mathrm{C}$ in the high frequency range.

Figure 5

Low temperature $(T=25\mathrm{K})$ Raman spectra of the samples doped with ${}^{12}\mathrm{C}$ and ${}^{13}\mathrm{C}$ showing the LVMs arising from dicarbon centers.

Figure 6

Raman spectra of the as-grown (a) and annealed (b) sample doped with ${}^{12}\mathrm{C}$.