Radiative recombination coefficient of free carriers in GaAs-AlGaAs quantum wells and its dependence on temperature

Abstract

The radiative recombination coefficient B, defined by dN/dt=dP/dt≡−BNP, of two-dimensional free carriers, N and P, in a selectively doped GaAs/n-Al0.3Ga0.7As quantum well was determined in the temperature range T between 15 and 300 K by measuring the decay time τ of photoluminescence from the quantum well with electron density N0=1×1012/cm2. It is found that B(=1/τN0) is 1.1–1.9×10−4 cm2/s at 300 K and increases as T is lowered, reaching 2.3×10−3 cm2/s (τ∼0.43 ns) at 15 K. The initial increase of B is nearly proportional to 1/T, whereas B tends to saturate at low temperature. These experimental findings are shown to be well explained by the theory of band-to-band recombination of two-dimensional carriers in quantum wells.