作　　者： ; ; ; ; ; ; ; ;

机构地区： 中国科学院长春光学精密机械与物理研究所激发态物理重点实验室

出　　处： 《发光学报》 2004年第3期277-282,共6页

摘　　要： 用等离子辅助分子束外延 (P MBE)的方法 ,在蓝宝石c平面上外延生长了MgxZn1 xO合金薄膜。在0≤x≤ 0 2范围内薄膜保持着ZnO的纤锌矿结构不变。X射线双晶衍射谱的结果表明生长的样品是单晶薄膜。据布喇格衍射公式计算得到 ,随着Mg含量的增加 ,薄膜的晶格常数c由 0 5 2 0 5nm减小到 0 5 1 85nm。室温光致发光谱出现很强的紫外近带发射 (NBE)峰 ,没有观察到深能级 (DL)发射 ,且随着Mg的掺入量的增加 ,紫外发射峰有明显的蓝移。透射光谱的结果表明 ,合金薄膜的吸收边随着Mg离子的掺入逐渐向高能侧移动 ,这与室温下光致发光的结果是相吻合的 ,并计算出随着x值增加 ,带隙宽度从 3 338eV逐渐展宽到3 6 82eV。通过研究Mg0 1 2 Zn0 88O样品的变温光谱 ,将紫外发射归结为束缚在施主能级上的束缚激子发射。并详细地研究了在整个温度变化过程中 ,束缚激子的两个不同的猝灭过程以及谱线的半峰全宽与温度变化的关系。 As a wide gap Ⅱ Ⅵ oxide semiconductor, ZnO is known to have a band gap of about 3 3 eV and large binding energy of excitons (59 meV) at room temperature. Recently, ZnO based semiconductors and related heterostructures are attracting more interest because of their promising optoelectronic applications in the ultraviolet wavelength range. To obtain the high performance light emitting devices, the key technique is to construct a heterojunction to realize double confinement action to electrons and photons in optoelectronic devices. Mg x Zn 1 x O alloy thin films have been studied extensively as their potential barrier materials. Mg x Zn 1 x O alloy thin films were fabricated on c plane sapphire (Al 2O 3) substrates by plasma assisted molecular beam epitaxy (P MBE). The films with different composition x , which is changed from 0 to 0 20, kept wurtzite crystal structure measured by X ray diffraction (XRD). X ray double crystal diffraction spectra show that the samples are single crystal films. As x value was increased from 0 to 0.20, the full width at half maximum (FWHM) of (002) oriented ZnO X ray rocking curve is broadened from 0 25° to 0 71° and the lattice constant of c axis is decreases from 0 520 5 nm to 0 518 5 nm. Photoluminescence (PL) spectra at room temperature(RT)exhibit an intense ultraviolet emission, without the deep level emission. With increasing x values, FWHMs of the emission peak change from 62 meV to 89 meV and peak positions shift to high energy side from 3 288 eV to 3 467 eV. The absorption edges of alloy thin films show the blue shifts with increasing x value in the transmission spectra at RT. The origin of the ultraviolet emission is studied by the measurements of the PL spectra at different temperature. The result shows that this emission comes from the recombination of neutral and ionized donor excitons. Two steps dissociation process of neutral donor exciton complexes is found, in which the thermal quench

关 键 词： 射线双晶衍射 光致发光

领　　域： [理学] [理学]