Interfacial, Electrical, and Band Alignment Characteristics of HfO2/Ge Stacks with In Situ-Formed SiO2 Interlayer by Plasma-Enhanced Atomic Layer Deposition

• Published in: Nanoscale research letters 2017-05, Vol.12 (1), p.1-370, Article 370
• Main Authors: Cao, Yan-Qiang, Wu, Bing, Wu, Di, Li, Ai-Dong
• Format: Article
• Language: English
• Subjects: 3rd International Conference on ALD Applications & 2016 China ALD conference; Alignment; Annealing; Atomic layer epitaxy; Capacitance; Chemistry and Materials Science; Conduction; Conduction bands; Deposition; Electrical measurement; Germanium; Germanium oxides; Hafnium oxide; Interlayers; Leakage current; Materials Science; Molecular Medicine; Nano Express; Nanochemistry; Nanoscale Science and Technology; Nanotechnology; Nanotechnology and Microengineering; Offsets; Silicates; Silicon; Silicon dioxide; Stacks; Thermal stability
• ISSN: 1931-7573; 1556-276X
• DOI: 10.1186/s11671-017-2083-z

In situ-formed SiO 2 was introduced into HfO 2 gate dielectrics on Ge substrate as interlayer by plasma-enhanced atomic layer deposition (PEALD). The interfacial, electrical, and band alignment characteristics of the HfO 2 /SiO 2 high-k gate dielectric stacks on Ge have been well investigated. It has been demonstrated that Si-O-Ge interlayer is formed on Ge surface during the in situ PEALD SiO 2 deposition process. This interlayer shows fantastic thermal stability during annealing without obvious Hf-silicates formation. In addition, it can also suppress the GeO 2 degradation. The electrical measurements show that capacitance equivalent thickness of 1.53 nm and a leakage current density of 2.1 × 10 −3 A/cm 2 at gate bias of V fb  + 1 V was obtained for the annealed sample. The conduction (valence) band offsets at the HfO 2 /SiO 2 /Ge interface with and without PDA are found to be 2.24 (2.69) and 2.48 (2.45) eV, respectively. These results indicate that in situ PEALD SiO 2 may be a promising interfacial control layer for the realization of high-quality Ge-based transistor devices. Moreover, it can be demonstrated that PEALD is a much more powerful technology for ultrathin interfacial control layer deposition than MOCVD.