Figure 1

(Color online) (a) Raman spectra of $\mathrm{Ga}{\mathrm{P}}_{0.985}{\mathrm{N}}_{0.015}$ (solid line) and GaP substrate (dashed line) in $z\left(YY\right)\overline{z}$ scattering geometry at room temperature with an excitation energy of $3.532\mathrm{eV}$. Three phonon modes are seen in the region shown in the inset, the ${\mathrm{TO}}_{\Gamma }$ phonon near $367{\mathrm{cm}}^{-1}$, the ${\mathrm{LO}}_X$ phonon near $388{\mathrm{cm}}^{-1}$, and the ${\mathrm{LO}}_{\Gamma }$ phonon near $403{\mathrm{cm}}^{-1}$, in the order of increasing energy. Inset: Fitting the result of the phonons using Lorentzian (symmetric—${\mathrm{TO}}_{\Gamma }$ and ${\mathrm{LO}}_X$ phonon) and Fano (Ref. 15) (asymmetric—${\mathrm{LO}}_{\Gamma }$ phonon) functions, respectively, for $\mathrm{Ga}{\mathrm{P}}_{0.985}{\mathrm{N}}_{0.015}$ with an excitation energy of $3.532\mathrm{eV}$. The experimental data are circles. (b) The Raman spectra of $\mathrm{Ga}{\mathrm{P}}_{0.99}{\mathrm{N}}_{0.01}$ in the same configuration, with an excitation energy of $4.104\mathrm{eV}$.Reuse & Permissions

Figure 2

(Color online) (a) Raman spectra of $\mathrm{Ga}{\mathrm{P}}_{0.985}{\mathrm{N}}_{0.015}$ at room temperature with excitation energies of $3.532\mathrm{eV}$ (dashed line) and $3.708\mathrm{eV}$ (solid line), respectively. (b) The excitation energy dependence (resonance profile) of the ${\mathrm{LO}}_{\Gamma }$ phonon intensity for the GaP substrate (empty diamonds), $\mathrm{Ga}{\mathrm{P}}_{0.09}{\mathrm{N}}_{0.01}$ (filled circles), and $\mathrm{Ga}{\mathrm{P}}_{0.98}{\mathrm{N}}_{0.02}$ (filled triangles). The data from other samples are not shown for clarity.Reuse & Permissions

Figure 3

(Color online) (a) The third numerical derivative of the imaginary part of the dielectric function $\left({ϵ}_2\right)$, of $\mathrm{Ga}{\mathrm{P}}_{0.9975}{\mathrm{N}}_{0.0025}$ (thick solid line), $\mathrm{Ga}{\mathrm{P}}_{0.985}{\mathrm{N}}_{0.015}$ (thin solid line), and $\mathrm{Ga}{\mathrm{P}}_{0.98}{\mathrm{N}}_{0.02}$ (dashed line). The empty squares represent fitted $E_1$ values. (b) The $E_1$ transition linewidth ${\Gamma }_1$ as a function of nitrogen concentration. The line is a guide to the eye.Reuse & Permissions

Figure 4

(Color online) Evolution of electronic state with respect to nitrogen concentration. The filled squares are the ${\mathrm{LO}}_{\Gamma }$ phonon intensity-resonance maxima, and the $E_1$ transition energy derived from the spectroscopic ellipsometry measurements (empty diamonds) is also shown for comparison. The line is a guide to the eye. Inset: Evolution of various electronic states with respect to nitrogen concentration. The filled circles and triangles are the ${\mathrm{LO}}_{\Gamma }$ phonon “linewidth” resonance maxima from previous RRS measurements in the visible range.[8] See the text for the explanation of each state. The dotted line $\left(E_0\right)$ is from the ellipsometry data of Ref. 9, and the empty squares are the photomodulated transmission data from Ref. 4. “BE” stands for the “band edge.”Reuse & Permissions

Figure 5

(Color online) (a) Raman spectra of $\mathrm{Ga}{\mathrm{As}}_{0.9959}{\mathrm{N}}_{0.0041}$ at $80\mathrm{K}$ with excitation energies of $3.001\mathrm{eV}$ (solid line) and $3.535\mathrm{eV}$ (dashed line), respectively. (b) The excitation energy dependence (resonance profile) of the ${\mathrm{LO}}_{\Gamma }$ phonon intensity for the undoped GaAs epilayer (empty diamonds), $\mathrm{Ga}{\mathrm{As}}_{0.9959}{\mathrm{N}}_{0.0041}$ (filled triangles), $\mathrm{Ga}{\mathrm{As}}_{0.9922}{\mathrm{N}}_{0.0078}$ (filled circles), $\mathrm{Ga}{\mathrm{As}}_{0.9898}{\mathrm{N}}_{0.0102}$ (empty triangles), and $\mathrm{Ga}{\mathrm{As}}_{0.9875}{\mathrm{N}}_{0.0125}$ (filled squares). The data from other samples are not shown for clarity.Reuse & Permissions

Figure 6

(Color online) Evolution of the electronic state with respect to nitrogen concentration. The filled circles are the ${\mathrm{LO}}_{\Gamma }$ phonon intensity-resonance maxima shifted by $-1.2\mathrm{eV}$. Shown for comparison are the ${\mathrm{LO}}_{\Gamma }$ phonon linewidth resonance maximum ${\mathrm{E}}_W$ (empty squares). Inset: The ${\mathrm{LO}}_{\Gamma }$ phonon scattering intensity-resonance maxima (crosses) and the ${\mathrm{LO}}_{\Gamma }$ phonon linewidth resonance maxima ${\mathrm{E}}_W$ and ${\mathrm{E}}_W^{\prime }$ (empty squares) in the visible range, which are reproduced from Fig. 2 of Ref. 10. See text.Reuse & Permissions