ZnMgO/ZnO异质结构中极化对二维电子气的影响
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摘要
基于ZnMgO/ZnO异质结构模型,从压电极化对应变弛豫度的依赖关系出发,通过自洽求解一维泊松-薛定谔方程,研究了ZnMgO势垒层的厚度、Mg组分和应变弛豫度对ZnMgO/ZnO异质界面处二维电子气(2DEG)的分布、面密度等性质的影响,并结合极化和能带偏移对计算结果进行了分析讨论。结果表明通过改变Mg组分和应变弛豫度可以调节异质界面两边的极化强度不连续性,进而有效地调控异质结中的二维电子气。
Based on the model of ZnMgO/ZnO heterostructure with relaxation-dependent piezoelectric polarization,the distribution and the sheet concentration of two-dimensional electron gas(2DEG)in heterointerface for different structural parameters were studied by solving the one-dimensional Poisson and Schrdinger equations self-consistently.The influences of the thickness of ZnMgO barrier,the Mg content and the degree of strain relaxation were investigated separately,and analyses for the corresponding results concerned with the polarization and the band offset were conducted.The computational results indicated that the polarization can be changed by altering the Mg content and the degree of strain relaxation,and thus the 2DEG can be controlled effectively.
Based on the model of ZnMgO/ZnO heterostructure with relaxation-dependent piezoelectric polarization,the distribution and the sheet concentration of two-dimensional electron gas(2DEG)in heterointerface for different structural parameters were studied by solving the one-dimensional Poisson and Schrdinger equations self-consistently.The influences of the thickness of ZnMgO barrier,the Mg content and the degree of strain relaxation were investigated separately,and analyses for the corresponding results concerned with the polarization and the band offset were conducted.The computational results indicated that the polarization can be changed by altering the Mg content and the degree of strain relaxation,and thus the 2DEG can be controlled effectively.
引文
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2 Bernardini F,Fiorentini V,Vanderbilt D.Spontaneous polarization and piezoelectric constants ofⅢ-Ⅴnitrides[J].Phys Rev B,1997,56(16):R10024
3 Tampo H,Shibata H,Matsubara K,et al.Two-dimensional electron gas in Zn polar ZnMgO/ZnO heterostructures grown by radical source molecular beam epitaxy[J].Appl Phys Lett,2006,89(13):132113
4 Tampo H,Shibata H,Maejima K,et al.Polarization-induced two-dimensional electron gases in ZnMgO/ZnO heterostructures[J].Appl Phys Lett,2008,93(20):202104
5 Tsukazaki A,Ohtomo A,Kita T,et al.Quantum hall effect in polar oxide heterostructures[J].Science,2007,315:1388
6 Tsukazaki A,Ohtomo A,Nakano M,et al.Photoinduced insulator-to-metal transition in ZnO/Mg0.15Zn0.85O heterostructures[J].Appl Phys Lett,2008,92(5):052105
7 Tsukazaki A,Yuji H,Akasaka S,et al.High electron mobility exceeding 104 cm2 V-1s-1 in MgxZn1-xO/ZnO single heterostructures grown by molecular beam epitaxy[J].Appl Phys Express,2008,1(5):055004
8 Tsukazaki A,Ohtomo A,Kawasaki M,et al.Spin susceptibility and effective mass of two-dimensional electrons in MgxZn1-xO/ZnO heterostructures[J].Phys Rev B,2008,78(23):233308
9 Tsukazaki A,Akasaka S,Nakahara K,et al.Observation of the fractional quantum Hall effect in an oxide[J].Nat Mater,2010,9(11):889
10 Ye J D,Pannirselvam S,Lim S T,et al.Two-dimensional electron gas in Zn-polar ZnMgO/ZnO heterostructure grown by metal-organic vapor phase epitaxy[J].Appl Phys Lett,2010,97(11):111908
11 Zhang Y,Gu S L,Ye J D,et al.Two-dimensional electron Gas in ZnMgO/ZnO heterostructures[J].Acta Phys Sinica,2013,62(15):150202(in Chinese)张阳,顾书林,叶建东,等.ZnMgO/ZnO异质结构中二维电子气的研究[J].物理学报,2013,62(15):150202
12 Yano M,Hashimoto K,Fujimoto K,et al.Polarization-induced two-dimensional electron gas at MgxZn1-xO/ZnO heterointerface[J].J Cryst Growth,2007,301-302:353
13 Shen D Z,Mei Z X,Liang H L,et al.ZnO-based matierial,heterojunction and photoelctronic device[J].Chinese J Luminescence,2014,35(1):1(in Chinese)申德振,梅增霞,梁会力,等.氧化锌基材料、异质结构及光电器件[J].发光学报,2014,35(1):1
14 Tampo H,Shibata H,Maejima K,et al.Band profiles of ZnMgO/ZnO heterostructures confirmed by Kelvin probeforce microscopy[J].Appl Phys Lett,2009,94(24):242107
15 Malashevich A,Vanderbilt D.First-principles study of polarization in Zn1-x MgxO[J].Phys Rev B,2007,75(4):045106
16 Bretagnon T,Lefebvre P,Guillet T,et al.Barrier composition dependence of the internal electric fieldin ZnO/Zn1-xMgxO quantum wells[J].Appl Phys Lett,2007,90(20):201912
17 Jogai B.Influence of surface states on the two-dimensional electron gas in AlGaN/GaN heterojunction field-effect transistors[J].J Appl Phys,2003,93(3):1631
18 Kong Y C,Zheng Y D,Zhou C H,et al.Influence of polarization and doping in AlGaN barrier on the two-dimensional electron-gas in AlGaN/GaN heterostructure[J].Acta Phys Sinica,2004,53(7):2320(in Chinese)孔月婵,郑有炓,周春红,等.AlGaN/GaN异质结构中极化与势垒层掺杂对二维电子气的影响[J].物理学报,2004,53(7):2320