Photoluminescence measurements on solar cell materials: chalcopyrites and kesterites

Doctoral thesis (2011)

The chalcopyrite Cu(In,Ga)Se2 is by now an established semiconductor for thin film solar cells. Its electrical properties is governed by native defects as for example copper vacancies VCu. However despite ... [more ▼]

The chalcopyrite Cu(In,Ga)Se2 is by now an established semiconductor for thin film solar cells. Its electrical properties is governed by native defects as for example copper vacancies VCu. However despite the good efficiencies, not much is known about the chemical nature of the defects responsible for the doping. The symmetry of the defects might be one way to determine their chemical nature. The symmetry of the defects will be investigated in this Ph.D. thesis by polarisation dependent photoluminescence measurements on epitaxial CuInSe2 and CuGaSe2 samples and on a CuInSe2 crystal. One major concern in fabricating thin film solar cells from the chalcopyrite Cu(In,Ga)Se2 is the indium price. One possibility to overcome this drawback is to replace the group III element indium by isoelectrical substitution by more abundant elements like zinc and tin, from the second and fourth group of the periodic table. This leads from the chalcopyrite CuInSe2 to the kesterite Cu2ZnSnSe4. However, synthesizing a quaternary compound, additional secondary and ternary phases become an important issue. In this Ph.D. thesis photoluminescence and X-ray diffraction results will be presented and their strengths and limits in the identification of secondary and ternary phases will be discussed. As kesterite is expected to be, similar to the chalcopyrites, a natively doped semiconductor, the defects will play a crucial role for the device properties. Therefore, in the third part of the Ph.D. thesis photoluminescence results on defects in kesterites, measured on PVD grown kesterite samples, will be discussed. [less ▲]

Shallow defects in Cu2ZnSnS4

in Physica B: Condensed Matter (2009), 404(23-24), 4949-4952