Temperature dependence of photoluminescence decay time in tunneling bi-quantum-well structures

We studied the nonresonant electron tunneling time in tunneling bi-quantum-well structures with a pump-probe photoluminescence (PL) system using optical mixing. The PL decay time of narrow wells for an Al_xGa_1−xAs (x=0.51) barrier of 4.0 nm, determined by tunneling, decreases from 40 ps to 24 ps as the temperature increases from 6K to 132K. We attribute this to electrons in an exciton state thermalizing into free electrons having a faster tunneling rate.