ABSTRACT
First thin films of Pb-Sb-S-, Sn-Sb-S- and Sn-Bi-S-compounds were deposited. Structural characterization of the deposited thin films by X-ray powder diffraction permits a rough classification in different growth regimes depending mainly on substrate temperature and composition. Refraction index, absorption coefficients, and band gap values where estimated from optical transmission measurements. The optical absorption in the visible spectrum region is very high. Band gap values range between 1.1 to 2.0 eV. Electrical characterization of the thin films was carried out by conductivity and thermopower measurements. Values of obtained specific resistivities range from 0.02 to >7×107 Ωcm. Thermopower measurements show that Sn-Sb-S and Sn-Bi-S thin films could be prepared either with p-type or with n-type conductivity depending on the S/Sn+(Sb,Bi) ratio. The highest measured Seebeck coefficients reach −2300 and +2500 µV/K for n- and p-type, respectively. First thin film solar cells were prepared by transferring the layer stacking sequence from CIS technology and substituting the CIS absorber layer. Diode characteristics estimated by J-V-measurements show strong photoconductivity and finally result in a first thin film solar cell with 1% efficiency (Voc= 208 mV, Jsc = 13.33 mAcm−2, FF = 37.9 %). Due to the specific properties found and the large optimization potential, this compound semiconductor family will be able to play an important role in optoelectronic applications
