Solution-processed, barrier-confined, and 1D nanostructure supported quasi-quantum well with large photoluminescence enhancement.
Solution-processed, barrier-confined, and 1D nanostructure supported quasi-quantum well with large photoluminescence enhancement.
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DOI：
10.1021/nn500465w
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发表时间：
2014-03
期刊：
影响因子：
17.1
通讯作者：
Keyou Yan;Lixia Zhang;Q. Kuang;Zhanhua Wei;Ya Yi;Jiannong Wang;Shihe Yang
中科院分区：
文献类型：
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作者：
Keyou Yan;Lixia Zhang;Q. Kuang;Zhanhua Wei;Ya Yi;Jiannong Wang;Shihe Yang
平面衬底支撑的半导体量子阱（QW）结构不适于在微型器件中操作，而独立的QW纳米结构，例如，纳米片和纳米带具有机械和环境不稳定性。因此，在各向异性和机械稳定的支撑纳米结构如纳米线和纳米片上形成高质量的QW结构是很有吸引力的。在此，我们报告了一个解决方案准异质外延生长势垒限制的准量子阱结构（ZnSe/CdSe/ZnSe）的ZnO纳米四脚体的支撑臂，它具有一维纳米线结构，通过离子交换和连续沉积组装相结合的路线。这导致了沿着纳米四足体臂的整个轴向方向的高度结晶和高度取向的准量子阱，因为形成了过渡缓冲层（Zn（x）Cd（1-x）Se），从而减少了晶格失配和表面缺陷。值得注意的是，这种势垒限制的量子阱在单粒子水平上发射的激子光比异质结（HJ）型结构（ZnSe/CdSe，HJ）强17倍。从系综量子阱的时间分辨的光致发光表现出10 ns的寿命，对比鲜明的控制HJ样品的300 ps。单粒子PL谱和拉曼谱表明量子阱势垒层完全去除了HJ表面的陷阱态，恢复或提高了半导体层的光电性能。因此，在支撑纳米四脚体上的这种有意的异质外延生长协议实现了具有高机械鲁棒性和高光电质量的几微米长的QW结构。我们设想，集成在一维纳米结构上的量子阱将大大提高太阳能电池和生物探针等的性能。
Planar substrate supported semiconductor quantum well (QW) structures are not amenable to manipulation in miniature devices, while free-standing QW nanostructures, e.g., ultrathin nanosheets and nanoribbons, suffer from mechanical and environmental instability. Therefore, it is tempting to fashion high-quality QW structures on anisotropic and mechanically robust supporting nanostructures such as nanowires and nanoplates. Herein, we report a solution quasi-heteroepitaxial route for growing a barrier-confined quasi-QW structure (ZnSe/CdSe/ZnSe) on the supporting arms of ZnO nanotetrapods, which have a 1D nanowire structure, through the combination of ion exchange and successive deposition assembly. This resulted in highly crystalline and highly oriented quasi-QWs along the whole axial direction of the arms of the nanotetrapod because a transition buffer layer (Zn(x)Cd(1-x)Se) was formed and in turn reduced the lattice mismatch and surface defects. Significantly, such a barrier-confined QW emits excitonic light ∼17 times stronger than the heterojunction (HJ)-type structure (ZnSe/CdSe, HJ) at the single-particle level. Time-resolved photoluminescence from ensemble QWs exhibits a lifetime of 10 ns, contrasting sharply with ∼300 ps for the control HJ sample. Single-particle PL and Raman spectra suggest that the barrier layer of QW has completely removed the surface trap states on the HJ and restored or upgraded the photoelectric properties of the semiconductor layer. Therefore, this deliberate heteroepitaxial growth protocol on the supporting nanotetrapod has realized a several micrometer long QW structure with high mechanical robustness and high photoelectric quality. We envision that such QWs integrated on 1D nanostructures will largely improve the performance of solar cells and bioprobes, among others.