The collection efficiency of carrier photogenerated in the intrinsic region of strained InAsxP1−x/InP multiquantum well p-i-n structures is analyzed. The existence of a critical threshold built-in electric field value above which total carrier collection becomes possible is demonstrated. Maximized carrier collection and high output voltage are systematically reached for built-in electric field exceeding the critical value while similar structures operating with a substantially lower built-in electric field (e.g., identical well characteristics but thicker i region) yields nonoptimized collection of carrier in this area and altered voltage output. The slight dependence of the critical electric field with the carrier confinement level is revealed, stressing out the importance of thermally activated escape energy. Finally, the results are discussed in the context of photovoltaic devices showing substantial efficiency improvement for devices designed with built-in electric fields in excess of the threshold value.

Photocurrent and photoluminescence measurements have been performed on strained InAsxP1−x/InP multiquantum wells grown by chemical beam epitaxy, for arsenic content 0.25<x<0.65 and various well widths. The energies deduced from photocurrent spectra of well-resolved electron–heavy-hole and electron–light-hole fundamental excitonic transitions are compared with calculations within the envelope function formalism including strain effects. A conduction-band offset ratio QC of 0.70±0.02 is determined and is found to be independent of the arsenic composition in wells.

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Thermally detected optical absorption, reflectance, and photoreflectance of In(As,P)/InP quantum wells grown by gas source molecular beam epitaxy Quantum dot-like behavior of GaInNAs in GaInNAs/GaAs quantum wells grown by gas-source molecular-beam epitaxy J.Photoluminescence investigation of GaInP/GaAs multiple quantum wells grown on (001) and (311) B GaAs surfaces by gas source molecular beam epitaxy

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