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ZnO-Cu2O core-shell nanowires as stable and fast response photodetectors
Nano Energy ( IF 17.6 ) Pub Date : 2018-06-21 , DOI: 10.1016/j.nanoen.2018.06.058
Pedram Ghamgosar , Federica Rigoni , Shujie You , Illia Dobryden , Mojtaba Gilzad Kohan , Anna Lucia Pellegrino , Isabella Concina , Nils Almqvist , Graziella Malandrino , Alberto Vomiero

In this work, we present all-oxide p-n junction core-shell nanowires (NWs) as fast and stable self-powered photodetectors. Hydrothermally grown n-type ZnO NWs were conformal covered by different thicknesses (up to 420 nm) of p-type copper oxide layers through metalorganic chemical vapor deposition (MOCVD). The ZnO NWs exhibit a single crystalline Wurtzite structure, preferentially grown along the [002] direction, and energy gap Eg = 3.24 eV. Depending on the deposition temperature, the copper oxide shell exhibits either a crystalline cubic structure of pure Cu2O phase (MOCVD at 250 °C) or a cubic structure of Cu2O with the presence of CuO phase impurities (MOCVD at 300 °C), with energy gap of 2.48 eV. The electrical measurements indicate the formation of a p-n junction after the deposition of the copper oxide layer. The core-shell photodetectors present a photoresponsivity at 0 V bias voltage up to 7.7 µA/W and time response ≤ 0.09 s, the fastest ever reported for oxide photodetectors in the visible range, and among the fastest including photodetectors with response limited to the UV region. The bare ZnO NWs have slow photoresponsivity, without recovery after the end of photo-stimulation. The fast time response for the core-shell structures is due to the presence of the p-n junctions, which enables fast exciton separation and charge extraction. Additionally, the suitable electronic structure of the ZnO-Cu2O heterojunction enables self-powering of the device at 0 V bias voltage. These results represent a significant advancement in the development of low-cost, high efficiency and self-powered photodetectors, highlighting the need of fine tuning the morphology, composition and electronic properties of p-n junctions to maximize device performances.



中文翻译:

ZnO-Cu 2 O核壳纳米线作为稳定和快速响应的光电探测器

在这项工作中,我们提出了全氧化物pn结核壳纳米线(NWs)作为快速,稳定的自供电光电探测器。水热生长的n型ZnO NW通过金属有机化学气相沉积(MOCVD)保形地覆盖了不同厚度(最大420 nm)的p型氧化铜层。ZnO NWs具有单晶纤锌矿结构,优先沿[002]方向生长,能隙E g = 3.24 eV。取决于沉积温度,氧化铜壳呈现纯Cu 2 O相的晶体立方结构(在250°C下进行MOCVD)或Cu 2的立方结构O存在CuO相杂质(在300°C下进行MOCVD),能隙为2.48 eV。电学测量表明在沉积氧化铜层之后形成了pn结。核壳光电探测器在0 V偏置电压下的光响应高达7.7 µA / W,时间响应≤0.09 s,是可见光范围内氧化物光电探测器中报道最快的,并且是响应速度仅限于紫外线的最快的光电探测器。地区。裸露的ZnO NW具有缓慢的光响应性,在光刺激结束后没有恢复。核-壳结构的快速时间响应归因于pn结的存在,这使快速激子分离和电荷提取成为可能。此外,ZnO-Cu 2的合适电子结构O异质结使器件能够在0 V偏置电压下自供电。这些结果代表了低成本,高效率和自供电光电检测器开发的重大进步,突出显示了需要微调pn结的形态,组成和电子性能以最大化器件性能的需求。

更新日期:2018-06-21
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