Piezoelectric Carrier Confinement by Lattice Mismatch at ZnO/Zn0.6Mg0.4O Heterointerface
Piezoelectric Carrier Confinement by Lattice Mismatch at ZnO/Zn0.6Mg0.4O Heterointerface
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DOI：
10.1143/jjap.43.l1372
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发表时间：
2004-10
影响因子：
1.5
通讯作者：
K. Koike;K. Hama;I. Nakashima;Gen-you Takada;M. Ozaki;K. Ogata;S. Sasa;M. Inoue;M. Yano
中科院分区：
文献类型：
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作者：
K. Koike;K. Hama;I. Nakashima;Gen-you Takada;M. Ozaki;K. Ogata;S. Sasa;M. Inoue;M. Yano
本文描述了一个强的压电载流子限制在ZnO/Zn0.6Mg0.4O异质界面上生长的a平面蓝宝石衬底上的分子束外延。ZnO/Zn0.6Mg0.4O双异质结结构的生长没有故意掺杂和电子的深势阱的形成证实了阴极发光和透射光谱。在4.5 K的光致发光光谱由一个强烈的近带边发射在3.359 eV和一个广泛的和弱的峰值上的低能量侧。霍尔效应测量结果表明，该材料为n型导电，载流子浓度高达1.2×1013 cm-2。在300 K和77 K下的迁移率分别为约170 cm 2/V·s和约400 cm 2/V·s，在较低温度下没有劣化，这些值远高于在a面蓝宝石衬底上生长的厚单层ZnO薄膜。我们将这些光学和电学性质归因于应变ZnO阱中的压电极化在ZnO/Zn0.6Mg0.4O异质界面处形成二维电子气。
This paper describes a strong piezoelectric carrier confinement at a ZnO/Zn0.6Mg0.4O heterointerface grown on an a-plane sapphire substrate by molecular beam epitaxy. A ZnO/Zn0.6Mg0.4O double-heterojunction structure was grown without intentional doping and the formation of a deep potential well for electrons was confirmed using cathodoluminescence and transmittance spectra. Photoluminescence spectra at 4.5 K consisted of an intense near-band-edge emission at 3.359 eV and a broad and weak peak on the low-energy side. The results of Hall effect measurement revealed that the conduction is n-type with a high carrier concentration of ∼1.2×1013 cm-2. The mobilities are ∼170 cm2/V·s at 300 K and ∼400 cm2/V·s at 77 K without deterioration at lower temperatures; these values are much higher than those of a thick single-layer ZnO film grown on an a-plane sapphire substrate. We attribute these optical and electrical properties to the formation of two-dimensional electron gas at the ZnO/Zn0.6Mg0.4O heterointerface by the piezoelectric polarization in a strained ZnO well.