Self-organized Formation of Ge-based Two-dimensional Crystals and Control of Crystalline Structure and Electronic State

2019 Fiscal Year Final Research Report

• Project/Area Number: 18K19020
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 29:Applied condensed matter physics and related fields
• Research Institution: Nagoya University
• Principal Investigator: Ohta Akio 名古屋大学, 工学研究科, 助教 (10553620)
• Co-Investigator(Kenkyū-buntansha): 黒澤 昌志 名古屋大学, 工学研究科, 講師 (40715439) ; 洗平 昌晃 名古屋大学, 未来材料・システム研究所, 助教 (20537427)
• Project Period (FY): 2018-06-29 – 2020-03-31
• Keywords: ゲルマニウム / 二次元結晶 / 表面偏析 / 電子状態 / ポストグラフェン

Outline of Final Research Achievements

We have studied the chemical and crystallographic structures of vacuum evaporated Al/Ge(111) before and after the thermal annealing to form the germenium (Ge) two dimensional (2D) crystals on the surface by the control of Ge segregation from Al. Hetero-epitaxial Al layer was found to be grown on Ge(111) substrate by controls of the Al thickness and deposition rate during the vacuum evaporation, which Al surface becomes the template of crystallographic structure of segregated Ge layer. The surface flattening and Ge segregation on Al/Ge(111) structure by the annealing have been systematically investigated, and the sub-nm-thick ultrathin segragated-Ge crystalline can be formed on the hetero-epitaxial Al surface.

Free Research Field

半導体工学

Academic Significance and Societal Importance of the Research Achievements

ポストグラフェン材料として注目されているGe原子の二次元結晶の形成は、これまでに清浄化した単結晶金属表面上へのGe原子の蒸着により行われてきた。これに対して、本研究では、Geと共晶反応を示すAl薄膜をGeウェハ上にヘテロエピタキシャル成長し、基板加熱や熱処理に伴うGe原子のAl薄層中への固溶と表面偏析を制御することで、サブナノメートルのGe結晶を成長できることを明らかにすることができた。