Formation of two-dimensional electron gas and enhancement of electron mobility by Zn polar ZnMgO/ZnO heterostructures

H. Tampo, H. Shibata, K. Matsubara, A. Yamada, P. Fons, M. Yamagata, H. Kanie, S. Niki

研究成果: Conference contribution


A two-dimensional electron gas (2DEG) was observed in Zn polar ZnMgO/ZnO (ZnMgO on ZnO) heterostructures grown by radical source molecular beam epitaxy. Reflection high energy electron diffraction patterns taken during the growth of the ZnMgO layer remained streaky; x-ray diffraction measurements showed no evidence of phase separation for up 44 % Mg composition. These results shows that the high quality ZnMgO layers up to 44 % Mg composition were obtained without phase separation. The electron mobility of the ZnMgO/ZnO heterostructures dramatically increased with increasing Mg composition and the electron mobility (μ∼250 cm2/Vs) at RT reached a value more than twice that of an undoped ZnO layer (μ∼100 cm2/Vs) due to the 2DEG formation. The carrier concentration in turn reached values as high as ∼1×1013 cm-2 and remained nearly constant regardless of Mg composition. Strong confinement of electrons at the ZnMgO/ZnO interface was confirmed by C-V measurements with a concentration of over 4×1019 cm-3. Temperature-dependent Hall measurements of ZnMgO/ZnO heterostructures also exhibited properties associated with well defined heterostructures. The Hall mobility increased monotonically with decreasing temperature, reaching a value of 2750 cm2/Vs at 4 K. Zn polar "ZnMgO on ZnO" structures are easy to adapt to a top-gate device. These results open new possibilities for high electron mobility transistors (HEMTs) based upon ZnO based materials.

ホスト出版物のタイトルZinc Oxide Materials and Devices II
出版ステータスPublished - 2007 5 24
イベントZinc Oxide Materials and Devices II - San Jose, CA, United States
継続期間: 2007 1 212007 1 24


名前Proceedings of SPIE - The International Society for Optical Engineering


ConferenceZinc Oxide Materials and Devices II
国/地域United States
CitySan Jose, CA

ASJC Scopus subject areas

  • 電子材料、光学材料、および磁性材料
  • 凝縮系物理学
  • コンピュータ サイエンスの応用
  • 応用数学
  • 電子工学および電気工学


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