Carrier distribution in asymmetric dual quantum wells

Abstract

The carrier density distribution in MQWs is investigated using asymmetric dual quantum wells (ADQWs). The ADQWs consist of a stake of double quantum wells with different well widths. The corresponding spontaneous emission for each well is centered on 0.8 micrometers and 0.83 micrometers , respectively. The carrier recombination in each quantum well can be distinguished by the EL spectrum. We theoretically calculate the EL spectrum of the ADQWs using the multi-band effective mass theory and density matrix formalism with different carrier distribution condition. In the multi-band effective mass theory, valence band mixing is taken into account by a 4 X 4 Luttinger-Kohn Hamiltonian. A Lorentzian lineshape function is used to include the intraband relaxation and lineshape broadening. The comparison of the calculated results with the experimentally measured EL spectrum and TE/TM mode ratio is given. At 200mA injection current,the theoretical EL spectrum shows very good agreement with the experimental results when the carrier density in the p-side well is 17 percent higher than that in the n-side well. Decreasing the injection current, the uniformity of the carrier density distribution becomes better. The reasons for the behavior of the carrier distributions are briefly discussed.