Session K40 - Poster Session II.
POSTER session, Tuesday afternoon, March 13
Exhibit Hall, Washington State Convention Center
Lattice-mismatched (Indium-rich) InGaAs heterostructures grown on InP substrates are strong candidates for thermophotovoltaic cells, devices that convert thermal radiation into electricity. For this application, recombination processes are critical because they reduce the conversion efficiency of the cells. We are studying a set of incrementally lattice-mismatched InGaAs/InAsP double heterostructures. We measure the radiative efficiency as a function of excitation power at 77K to compare the rates of defect-related (nonradiative) and radiative recombination in these structures. The changeover between the nonradiative and radiative regimes with increasing excitation is clearly evident in the data. While increasing lattice-mismatch is expected to generate larger defect densities, which augments the nonradiative process, the increasing Indium concentration in the InGaAs also lowers the bandgap, which should reduce the radiative recombination rate. We present preliminary results on how the transition between defect-dominated and radiative recombination depends on lattice-mismatch.