中国物理B ›› 2011, Vol. 20 ›› Issue (9): 97106-097106.doi: 10.1088/1674-1056/20/9/097106

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Influence of thermal stress on the relative permittivity of the AlGaN barrier layer in an AlGaN/GaN heterostructure Schottky contacts

陈弘1, 王占国2, 吕元杰3, 林兆军3, 张宇3, 孟令国3, 曹芝芳3, 栾崇彪3   

  1. (1)Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; (2)Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China; (3)School of Physics, Shandong University, Jinan 250100, China
  • 收稿日期:2010-12-23 修回日期:2011-03-28 出版日期:2011-09-15 发布日期:2011-09-15

Influence of thermal stress on the relative permittivity of the AlGaN barrier layer in an AlGaN/GaN heterostructure Schottky contacts

Lü Yuan-Jie(吕元杰)a), Lin Zhao-Jun(林兆军) a)†, Zhang Yu(张宇)a), Meng Ling-Guo(孟令国)a), Cao Zhi-Fang(曹芝芳) a), Luan Chong-Biao(栾崇彪)a), Chen Hong(陈弘)b), and Wang Zhan-Guo(王占国)c)   

  1. a School of Physics, Shandong University, Jinan 250100, China; b Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; c Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
  • Received:2010-12-23 Revised:2011-03-28 Online:2011-09-15 Published:2011-09-15

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摘要： Ni Schottky contacts on AlGaN/GaN heterostructures were fabricated. Some samples were thermally treated in a furnace with N2 ambience at 600 °C for different times (0.5 h, 4.5 h, 10.5 h, 18 h, 33 h, 48 h, and 72 h), the others were thermally treated for 0.5 h at different temperatures (500 °C, 600 °C, 700 °C, and 800 °C). With the measured current—voltage (I—V) and capacitance—voltage (C—V) curves and by self-consistently solving Schrodinger's and Poisson's equations, we found that the relative permittivity of the AlGaN barrier layer was related to the piezoelectric and the spontaneous polarization of the AlGaN barrier layer. The relative permittivity was in proportion to the strain of the AlGaN barrier layer. The relative permittivity and the strain reduced with the increased thermal stress time until the AlGaN barrier totally relaxed (after 18 h at 600 °C in the current study), and then the relative permittivity was almost a constant with the increased thermal stress time. When the sample was treated at 800 °C for 0.5 h, the relative permittivity was less than the constant due to the huge diffusion of the contact metal atoms. Considering the relation between the relative permittivity of the AlGaN barrier layer and the converse piezoelectric effect, the conclusion can be made that a moderate thermal stress can restrain the converse piezoelectric effect and can improve the stability of AlGaN/GaN heterostructure devices.

关键词: AlGaN/GaN heterostructures, relative permittivity of AlGaN barrier layer, converse piezoelectric effect

Abstract: Ni Schottky contacts on AlGaN/GaN heterostructures were fabricated. Some samples were thermally treated in a furnace with N2 ambience at 600 °C for different times (0.5 h, 4.5 h, 10.5 h, 18 h, 33 h, 48 h, and 72 h), the others were thermally treated for 0.5 h at different temperatures (500 °C, 600 °C, 700 °C, and 800 °C). With the measured current—voltage (I—V) and capacitance—voltage (C—V) curves and by self-consistently solving Schrodinger's and Poisson's equations, we found that the relative permittivity of the AlGaN barrier layer was related to the piezoelectric and the spontaneous polarization of the AlGaN barrier layer. The relative permittivity was in proportion to the strain of the AlGaN barrier layer. The relative permittivity and the strain reduced with the increased thermal stress time until the AlGaN barrier totally relaxed (after 18 h at 600 °C in the current study), and then the relative permittivity was almost a constant with the increased thermal stress time. When the sample was treated at 800 °C for 0.5 h, the relative permittivity was less than the constant due to the huge diffusion of the contact metal atoms. Considering the relation between the relative permittivity of the AlGaN barrier layer and the converse piezoelectric effect, the conclusion can be made that a moderate thermal stress can restrain the converse piezoelectric effect and can improve the stability of AlGaN/GaN heterostructure devices.

Key words: AlGaN/GaN heterostructures, relative permittivity of AlGaN barrier layer, converse piezoelectric effect

中图分类号:  (III-V semiconductors)

  • 71.55.Eq
77.22.Ch (Permittivity (dielectric function)) 77.22.Ej (Polarization and depolarization)