Band anticrossing in diluted AlxGa1−xAs1−yNy (x⩽0.37,y⩽0.04)

We show that the conduction band structure of dilute ${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}{\mathrm{As}}_{1-y}{\mathrm{N}}_y$ with $x⩽0.37$ and $y⩽0.04$ can be described consistently by the experimentally motivated band anticrossing model. The interband transition energies $E_{-}$ , $E_{-}+{\Delta }_0$ , and $E_{+}$ have been derived from a full line shape fit to photomodulated reflectance (PR) spectra recorded at room temperature. The PR data were taken (a) from a series of ${\mathrm{Al}}_{0.06}{\mathrm{Ga}}_{0.94}{\mathrm{As}}_{1-y}{\mathrm{N}}_y$ samples with $y⩽0.04$ and (b) from a set of ${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}{\mathrm{As}}_{0.99}{\mathrm{N}}_{0.01}$ layers with $x⩽0.37$ . The latter series covers the range of Al concentrations where the ${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$ band gap energy $E_{\mathrm{M}}$ is expected to cross the nitrogen-induced energy level $E_{\mathrm{N}}$ . The resulting nitrogen- and Al-concentration dependent interband transition energies are described by the band anticrossing model using a matrix element for the coupling between the nitrogen-induced states and the extend lowest conduction band states of $C_{\mathrm{MN}}=2.32\mathrm{eV}$ and a nitrogen level energy $E_{\mathrm{N}}=(1.625+0.069x)\mathrm{eV}$ , the latter measured with respect to the GaAs valence band edge.