Atomic layer deposition of crystalline SrHfO3 directly on Ge (001) for high-k dielectric applications
Abstract
The current work explores the crystalline perovskite oxide, strontium hafnate, as a potential high-k gate dielectric for Ge-based transistors. SrHfO3 (SHO) is grown directly on Ge by atomic layer deposition and becomes crystalline with epitaxial registry after post-deposition vacuum annealing at ∼700 °C for 5 min. The 2 × 1 reconstructed, clean Ge (001) surface is a necessary template to achieve crystalline films upon annealing. The SHO films exhibit excellent crystallinity, as shown by x-ray diffraction and transmission electron microscopy. The SHO films have favorable electronic properties for consideration as a high-k gate dielectric on Ge, with satisfactory band offsets (>2 eV), low leakage current (<10−5 A/cm2 at an applied field of 1 MV/cm) at an equivalent oxide thickness of 1 nm, and a reasonable dielectric constant (k ∼ 18). The interface trap density (Dit) is estimated to be as low as ∼2 × 1012 cm−2 eV−1 under the current growth and anneal conditions. Some interfacial reaction is observed between SHO and Ge at temperatures above ∼650 °C, which may contribute to increased Dit value. This study confirms the potential for crystalline oxides grown directly on Ge by atomic layer deposition for advanced electronic applications.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Feb 03, 2015
- Source ID
- 10.1063/1.4906953
Entities
People
- Agham Posadas
- Aiting Jiang
- Alexander A Demkov
- Chengqing Hu
- David J Smith
- Edward T. Yu
- John G Ekerdt
- Martin D. Mcdaniel
- Sirong Lu
- Thong Q. Ngo
Organizations
- Air Force Office of Scientific Research
- Arizona State University
- National Science Foundation
- Office of Naval Research
- University of Texas at Austin