⁶³Cu-NMR studies of crystalline and thin-film CuInSe₂

Polycrystalline n- and p-type CuInSe₂ (CIS) has been examined via ⁶³Cu-NMR. Results show that a combination of interactions significantly affect the response including dipolar, quadrupolar and chemical shifts (possibly paramagnetic + Knight shift). In order to separate the interactions, studies have been performed, at various frequencies on materials of different composition. These measurements are valuable since they provide information directly related to the defect structure, and Cu⁺ migration in CIS. Most interactions have been modeled successfully. However, the origin of the temperature-dependent paramagnetic shift is suspected to be linked to carrier concentration but may arise from complex interactions between unpaired electron spins at neighboring defect sites. One of the goals of this work is to ascertain the degree by which nuclear magnetism is affected through intrinsic defects and conduction electrons. Such information is important for the characterization of electronic properties and ultimately device performance.