Growth and device properties of ALD deposited ZnO films for CIGS solar cells

We report the structural, optical, and electrical properties of an atomic layer deposited ZnO thin films in the temperature range of 80-180 degrees C. Also, the device characteristics of the CIGS solar cells with the ALD-ZnO buffer layers were investigated. The thickness and grain sizes of the ZnO were increased with an increase of temperature. All ZnO films exhibited the preferred crystal orientation along the (100) plane except the films grown at 80 degrees C showed along the (002) plane. The optical energy band gap of the ZnO was decreased from 3.30 to 3.29 eV with an increase of temperature. The electrical resistivity decreased from 6.2 to 5.6 x 10-3 Omega cm, while the mobility and the carrier concentrations increased from 1.7 to 21.6 cm(2)/V.s and from 6.0 x 1018 to 2.0 x 1020 cm(-3), respectively. The fabricated CIGS solar cells using a 70 nm-thick ZnO film deposited at 100 degrees C, exhibited the best device characteristics of the FF, Jsc, and PCE as 63.48%, 28.84 mA/cm(2), and 8.59%, respectively.

Automated summary

The properties of atomic layer deposited ZnO thin films in the temperature range of 80-180 degrees C were studied, showing an increase in thickness and grain sizes with temperature. The ZnO films exhibited preferred crystal orientation along the (100) plane, except for those grown at 80 degrees C. The electrical resistivity decreased, while mobility and carrier concentrations increased with temperature. CIGS solar cells using a 70 nm-thick ZnO film deposited at 100 degrees C showed the best device characteristics.