Modeling of the impact of Se-vacancies on the electrical properties of Cu(In,Ga)Se2 films and junctions

Persistent Photoconductivity in Polycrystalline Cu(In,Ga)Se₂ Thin Films: Experiment Versus Theoretical Predictions

“…We examined the following situation: A sample is rapidly cooled from room temperature to the temperature of the experiment (i.e., the initial charge state concentration corresponds to the roomtemperature equilibrium; see calculations reported in [18]) and illuminated for 1 h, after which, the illumination is terminated. Moreover, the steady state (reached after illumination for a sufficiently long time) was also analyzed.…”

“…In our simulations, the same values of energetic parameters characterizing electronic transitions as in a previous report [18] were used. The parameters of the (V Se − V Cu ) complexes were E EC = 0.10 eV, E HC = 0.35 eV, E HE = 0.85 eV, and E EE = 0.80 eV (according to [17]).…”

“…Note that the dependence of time constants on capture cross sections [see (1)-(4)] differs from the linear dependence assumed in the traditional analysis of thermally activated emission (e.g., in DLTS); thus, the values of σ e and σ h in this analysis might differ from those obtained experimentally. The initial value of f A used in the simulations was 0.216, which is equal to the equilibrium f A at 300 K calculated in [18] for a sample with N sh , N T , and the configuration barriers given above (equilibrium values under other conditions can also be found in [18]). We assumed the same initial value at all temperatures of illumination; therefore, the simulated situation corresponds to the sample cooled rapidly from room temperature to the temperature of the experiment (frozen distribution of the metastable complexes).…”

On the magnitude of the persistent photoconductivity (PPC) effect in CIGS layers with and without sodium

“…For hole concentration >10 15 cm -3 in RT, f A values must be smaller than 0.5-0.6 [7]. It means that the increase of hole concentration should be between ~0.8N T and 2N T .…”

The Influence of the n-Side Doping on Metastable Defect Concentrations in Cu(In,Ga)Se₂ Evaluated From Space Charge Profiles

“…The explanation of metastable properties of CIGS by amphoteric character of (V Se -V Cu ) complex was proposed by Lany and Zunger [4], [9]. The detailed analysis of metastable properties of this defect and its influence on electrical properties of CIGS devices can be found in [10] and [11]. In our previous paper [11], we proposed a simple method of evaluation of metastable defect and shallow acceptor densities.…”