Carrier mass measurements in degenerate indium nitride

We present photoluminescence measurements under intense magnetic fields (B up to 30 T) in n-doped indium nitride samples with carrier concentration ranging from about 7.5×10¹⁷ cm^-3 to 5×10¹⁸ cm^-3. The observation of transitions involving several Landau levels permits to determine the carrier-reduced mass μ around the Γ point. Depending on the carrier concentration, we find μ ranging between 0.093m₀ and 0.107m₀ (m₀ is the electron mass in vacuum). This finding poses a lower limit to the electron effective mass, whose unexpectedly large value (mₑ≥0.093m₀) indicates that the sources of n doping in InN perturb strongly the crystal conduction band near its minimum.