Physical mechanisms of photoluminescence of InGaAs(N) alloy films grown by MOVPE

Reported here are some results of temperature and excitation power dependences of photoluminescence (PL) from the InGaAs(N) (In = 10.5%, 17.0% and N = 0-2.3%) alloy films grown at 530 °C and 600 °C by metalorganic vapour phase epitaxy (MOVPE). The InGaAs(N) alloy films emitting at room temperature in the wavelength (λ) range of 0.97-1.23 μm have been investigated. The low-temperature PL spectra in this set of samples are dominated by multiple peak emissions associated with both near-band-edge emission of InGaAs(N) (high energy peak, E_PH) and strongly localized states (lower energy peaks, E_PL) much lower than the InGaAs(N) band-gap. The temperature dependence of integrated PL intensity indicates the presence of non-radiative recombination centers with the localization energy (E_loc = 9.4-25.8 meV), which increased with increasing N concentration. Here we noted that E_loc are in agreement with the energy difference of E_PH and E_PL peaks. The α values extracted from the relation I_PL ∝ I_ex^α are used to examine the recombination process. In the N-containing layers it is demonstrated that free-excitons, not free-carriers, mainly govern the radiative recombination.