Diffusion coefficients of two mobile ions in three AB3In7VI12 single crystals (AB=Cu and Ag VI=Se or Te). Proposition of an equivalent electrical circuit

The interface effect on the I–V curves and analysis of ionic diffusion coefficients of polycrystalline CuIn4Te6

“…The compositional, structural, optical and electrical properties of this slice have been previously reported [24]. In-rich chalcopyrites of the Cu-In-Te (CIT) system can be considered as a mixed electronic and ionic conductor with one or two mobile ions [7,9,25]. In a similar way than in previous works on single crystals, graphite paint has been used as electrode in both slice faces to form an electrode/CIT/electrode solid state device, since it has been shown that it is a good ohmic contact between semiconductor and electrode [25].…”

“…From the evolution of conductivity as a function of t −1 it is possible to compute the chemical diffusion coefficients [7,9]. All conductivity data have been fitted to exponential decays of second order, as shown in Fig.…”

“…However, in MIECs with high ionic conductivity, strong effects are observed in the electrical properties due to their ionic motion. We have found that In rich chalcopyrites as CuIn 3 Te 5 , Cu 0.9 Ag 0.1 In 3 Te 5 and Cu 0.9 Ag 0.1 In 3 Se 5 belong to this kind of high ionic conductivity MIECs [7][8][9]. They show a resistance change under application of a constant potential that can be associated with the existence of two mobile ions blocked at the interface.…”

“…The existence of the DADP permits the Cu and In Cu 2+ motion through Cu vacant sites. AB n−3 -III n+1 -VI 2n compounds with n=4, 5,6,7,8,9 can be formed with a very similar structure and different number of DADPs depending on the n value [10]. In nanoscale MIECs with low ionic motion, new I-V relations under a slowly varying applied voltage may appear due to the ion motion [6].…”

“…The gradient in the ion electrochemical potential is the driving force for the ionic motion. In MIECs with two mobile ions and high diffusion coefficients as CuIn 3 Te 5 , Cu 0.9 Ag 0.1 In 3 Te 5 and Cu 0.9 Ag 0.1 In 3 Se 5 , the ions move a distance that alter their concentration along the sample and different compositions can appear in the bulk and at the interfaces due to the ionic accumulation produced when an external voltage is applied [7][8][9].…”