InGaN/GaN multiple-quantum well heterostructures for solar cells grown by MOVPE: case studies
Résumé
We investigate the influence of growth temperature, p ‐doping with bis‐cyclopentadienyl magnesium (Cp2Mg) and number N of multi‐quantum wells on the surface morphology, the electrical and optical properties of InGaN‐based solar cells grown by metal‐organic vapour phase epitaxy. Atomic force microscopy measurements show no influence of multiple‐quantum well number on the surface morphology, but a smoothing with the increase of the Cp2Mg flow. Electrochemical capacitance‐voltage profiling exhibits an increase of the Na‐Nd concentration when increasing the Cp2Mg flow from 250 to 700 sccm. X‐ray diffraction analysis and transmission electron microscopy measurements confirm completely strained quantum wells with similar superlattice period for N=5 to 30. Finally, first solar cells have been demonstrated with a maximum external quantum efficiency of 38% at 380 nm wavelength for N=30.