Excitation mechanisms of photoluminescence in double-barrier resonant-tunneling structures

The excitation mechanisms which lead to photoluminescence (PL) in the quantum wells of double-barrier resonant-tunneling structures are analyzed. It is shown that on an electron-tunneling resonance, in the present structures with wide depletion regions under bias, recombination occurs predominantly between electrons which tunnel into the quantum well and holes which are created in the thick GaAs contacts. These holes drift and diffuse to the barriers where they accumulate, and then tunnel into the well. The importance of photon recycling of photocreated carriers is demonstrated. Finally, the factors which control the variation of PL intensity with applied bias are discussed.