Investigation Of The Device Properties Of Cztse Thin Films For Solar Cells

Thin Film Solar Cell has received a considerable attention in the photovoltaic industry. While the efficiency of thin film amorphous silicon is about %14, the efficiency of Cu(In,Ga)Se2 (CIGS) thin film based solar cells ,is very popular in the recent year, reached the value of %20. But CIGS based solar cells have some constraints such as its extensive and large scale production in terms of availability of its constituent elements. On the other hand, Kesterit based solar cells such as Cu2ZnSnSe4 (CZTSe) have been more popular due to its constituent elements, such as Zn and Sn, are more abundant and less expensive than In and Ga. These new thin film structures are direct band gap semiconductor. Their absorption coefficient value is over 104 cm-1 and the band gap value of them is about in the range of 1.45-1.6 eV [1-4]. These values are close to the values for the ideal solar cell. In this work, Cu-Zn-SnSe compounds belonging to Kesterit family will be deposited as a thin film on n type Si wafer in a stacked layer form. Then Al/n-Si/p-CZTSe/Ag heterojunction structure was fabricated to get the device properties of this film. Temperature dependent current-voltage (I-V) measurements and frequency dependent capacitance-voltage (C-V) measurements were carried out to investigate the device characteristics. Device parameters such as diode ideality factor (n), barrier height, series and shunt resistances were obtained and the conduction mechanisms were analyzed in different temperature regions by the help of the I-V analysis. From C-V measurements, the built-in potential and the acceptordonor level densities were determined