Low-Temperature Iron-Induced Crystallization of Germanium Thin Films: Substrate-Dependent Structural and Electrical Properties
Journal of Raman Spectroscopy, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Publication Date: 2026
- Doi Number: 10.1002/jrs.70181
- Journal Name: Journal of Raman Spectroscopy
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Aerospace Database, Chemical Abstracts Core, Chimica, Compendex, Index Islamicus, INSPEC, Academic Search Ultimate (EBSCO), Materials Science & Engineering Collection (ProQuest), Technology Collection (ProQuest)
- Keywords: germanium thin films, iron-induced crystallization, metal-induced crystallization, Raman spectroscopy, substrate-dependent crystallization, X-ray diffraction
- Anadolu University Affiliated: Yes
Abstract
This study investigates iron-induced crystallization (Fe-IC) of amorphous germanium (α-Ge) thin films deposited on aluminum-doped zinc oxide (AZO) and crystalline silicon (c-Si) (100) substrates. A thin Fe interlayer effectively promotes the crystallization of α-Ge thin films during post-annealing at 400°C–500°C. Raman spectroscopy and X-ray diffraction (XRD) analyses reveal a clear amorphous-to-crystalline transition, accompanied by peak sharpening, linewidth reduction, and the development of a preferential Ge(111) orientation. The combined Raman–XRD analysis demonstrates progressive strain relaxation and grain growth, with significantly enhanced crystallization observed on c-Si compared to AZO substrates. Electrical measurements further show that Fe-assisted crystallization markedly improves charge transport, leading to ohmic behavior in AZO-based films and rectifying characteristics in c-Si–based structures. These findings establish Fe as an effective catalyst for low-temperature crystallization of Ge thin films and highlight the critical role of substrate properties in governing microstructural evolution and electrical performance.