Influence of Substrate Temperature and Sulfurization on Sputtered Cu2SnGe(S,Se)3 Thin Films for Solar Cell Application

• Published in: IEEE transactions on electron devices Vol. 69; no. 5; pp. 2488 - 2493
• Main Authors: Dubey, Mayank, Siddharth, Gaurav, Singh, Ruchi, Patel, Chandrabhan, Kumar, Sanjay, Htay, Myo Than, Atuchin, Victor V., Mukherjee, Shaibal
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.05.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Chemical vapor deposition; Crystal structure; Cu₂(Sn; dual-ion beam sputtering (DIBS); Energy gap; Ge)(S; Germanium; Glass substrates; Grain size; Ion beam sputtering; Optical properties; Photovoltaic cells; Room temperature; Se)₃ (CTGSSe; Soda-lime glass; Solar cells; Spectroellipsometry; substrate temperature; Substrates; Sulfur; Sulfurization; Surface morphology; Temperature; Thin films; Tin; X-ray diffraction
• DOI: 10.1109/TED.2022.3159509
• ISSN: 0018-9383

This work presents the influence of substrate temperature (<inline-formula> <tex-math notation="LaTeX">{T}_{\text{sub}} </tex-math></inline-formula>) and post-sulfurization on compositional, structural, electrical, and optical properties of dual-ion beam sputtering (DIBS)-grown Cu 2 (Sn,Ge)(S,Se) 3 (CTGSSe) thin films grown on a soda-lime glass (SLG) substrate using a single target. Post-sulfurization of CTGSSe thin films is carried out in a quartz tube chemical vapor deposition (CVD) system. X-ray diffraction (XRD) analysis reveals that the crystal structure of CTGSSe thin films is preferentially tetragonal with (112) and (204) lattice planes at <inline-formula> <tex-math notation="LaTeX">2\theta </tex-math></inline-formula> values of 27.3° and 47.3°, respectively. Field-emission scanning electron microscopy (SEM) has emphasized that the high <inline-formula> <tex-math notation="LaTeX">{T}_{\text{sub}} </tex-math></inline-formula> growth resulted in a larger grain size of 87 nm and better thin-film morphology. Spectroscopic ellipsometry (SE) analysis shows the bandgap values of 1.46-1.62 eV by varying <inline-formula> <tex-math notation="LaTeX">{T}_{\text{sub}} </tex-math></inline-formula> from room temperature (RT) to 300 °C. Furthermore, the bandgap widens from 1.56 to 1.64 eV in the CTGSSe thin films due to post-sulfurization.