Fabrication and Characterization of a Self-Powered n-Bi2Se3/p-Si Nanowire Bulk Heterojunction Broadband Photodetector

Abstract

In the present study, vacuum evaporation method is used to deposit Bi2Se3 film onto Si nanowires (NWs) to form bulk heterojunction for the first time. Its photodetector is self-powered, its detection wavelength ranges from 390 nm to 1700 nm and its responsivity reaches its highest value of 84.3 mA/W at 390 nm. In comparison to other Bi2Se3/Si photodetectors previously reported, its infrared detection length is the second longest and its response speed is the third fastest. Before the fabrication of the photodetector, we optimized the growth parameter of the Bi2Se3 film and the best Bi2Se3 film with atomic steps could finally be achieved. The electrical property measurement conducted by the physical property measurement system (PPMS) showed that the grown Bi2Se3 film was n-type conductive and had unique topological insulator properties, such as a metallic state, weak anti-localization (WAL) and linear magnetic resistance (LMR). Subsequently, we fabricated Si NWs by the metal-assisted chemical etching (MACE) method. The interspace between Si NWs and the height of Si NWs could be tuned by Ag deposition and chemical etching times, respectively. Finally, Si NWs fabricated with the Ag deposition time of 60 s and the etching time of 10 min was covered by the best Bi2Se3 film to be processed for the photodetector. The primary n-Bi2Se3/p-Si NWs photodetector that we fabricated can work in a self-powered mode and it has a broadband detection range and fast response speed, which indicates that it can serve as a promising silicon-based near- and mid-infrared photodetector.

Enhanced Photoresponse of High Crystalline Bi2Se3 Thin-Films Using Patterned Substrates

“…Meanwhile, the photo-detectors utilizing Bi 2 Te 3 /Bi 2 Se 3 /Bi 2 S 3 cascade heterostructure reveals a fast-response of 8 ms and a high-photoresponsivity of 103 mW/A at −1 V under 475 nm illumination. 56 A selfpowered n-Bi 2 Se 3 /p-Si nanowire bulk heterojunction device also shows a responsivity of 84.3 mA/W at 390 nm and its response time of 3 ms. 57 Compared to these heterojunction devices, the Bi 2 Se 3 /PSS has a simpler device structure, a fairly high photocurrent, a competitive photoswitching speed, and a strong absorption in a broad wavelength ranging from visible to near IR. Therefore, the topological insulator Bi 2 Se 3 grown on the PSS holds great promise for high-performance optoelectronic applications.…”

Research progress of silicon nanowires array photodetectors

“…2021 年，Asuo 等人 [81] 图 11 高性能 Si-NTCA/石墨烯光电探测器结构示意图 [81] Figure 11 Schematic diagram of high-performance Si-NTCA/graphene photodetector. [81] 21 / 33 2022 年，Wang 等人 [15] 通过真空热蒸发法获得了高质量的拓扑绝缘体 Bi 图 12 n-Bi 2 Se 3 /p-SiNWs 光电探测器在探测波长范围内的响应率和探测率 [14] Figure 12 Responsivity and detectivity of n-Bi 2 Se 3 /p-SiNWs photodetector in the detection wavelength range. [14] 图 13 高质量"共形"Si-NW/MoS 2 异质结光电探测器的制备流程 [83] Figure 13 Preparation process for high-quality "Conformal" Si-NW/MoS 2 heterojunction photodetector.…”

“…些特性使其成为制造各种半导体器件的关键元素 [1][2][3][4] 。硅具有较小的带隙、优越的光 捕获能力和快速的电荷传输能力，是构建宽带光电探测器的理想半导体。硅光电探 测器主要用于紫外到近红外(NIR)区域的光电探测 [5][6][7][8][9] 。然而，硅的间接带隙和有 限的吸收范围严重限制了硅基光电探测器的性能和应用。 为了改善硅基光电探测器的器件性能，人们对硅基进行纳米结构改造或构建互 补 半 导 体 异 质 结 [10][11][12][13][14] 。 在 这 些 方 案 中 ， 通 过 金 属 辅 助 化 学 蚀 刻 (Metal-Assisted Chemical Etching，MACE)制备的硅纳米结构(如硅纳米线或纳米柱等) ，因其拥有 卓越的收集光的能力及构建硅基/互补半导体异质结的潜力而备受关注。相关研究显 示，通过 MACE 制备的硅纳米结构可以有效拓宽硅基光电探测器的响应波段，在制 备柔性硅基光电探测器方面具有巨大的潜力 [15][16][17] [18] 指 出，超清洁硅片表面(即完全没有颗粒、有机杂质、金属杂质、天然氧化物、表面 微粗糙和吸附杂质的表面)对于实现超大规模集成生产至关重要。故而，对金属颗 粒的行为，特别是硅晶片表面上的贵金属离子和颗粒在湿式化学清洗溶液中的行为， 人们进行了广泛的研究，以了解金属沉积的基本机制以及如何将其从硅表面有效地 去除。 1994 年，Morinaga 等人 [19] 发现，贵金属阳离子可与硅的界面实现电荷转移，并 以金属状态沉积在硅表面，而在金属沉积物附近的硅被诱导氧化，被氧化的硅在稀 氢氟酸溶液中被溶解，从而导致硅表面出现凹坑和微观粗糙面。贵金属阳离子还原 是将硅的导带电子传导出去或者向硅的价带注入空穴来实现对硅的蚀刻。 图 1 给出了湿法蚀刻过程中硅表面上的铜沉积以及铜诱导蚀刻的机制。首先， 铜离子从硅衬底提取电子，并以金属铜的形式沉积在硅衬底上。由于铜原子核比硅 的电负性更高，因此会吸引硅中的电子，使铜带负电。附近的铜离子会沉积在铜核 周围，随着铜离子的持续沉积，铜核成为更大的颗粒，铜颗粒下方的硅表面释放出 与铜离子所需的电子，从而产生氧化硅 [19,20] 。在经过混有稀氢氟酸的过氧化氢溶液 处理后，硅表面会出现许多小孔；而对于没有金属颗粒的硅表面，并未观察到与初 始状态之间的明显差异。 图 1 金属辅助硅蚀刻(MACE)的微观解释 [19] Figure 1 Microscopic interpretation of Metal-Assisted Chemical Etching (MACE). [19] 1995 年，Morinaga 等人 [21] [22][23][24] 系统地研究了硅在含有氧化剂的氢氟酸水溶液中的…”

High performance and self-powered photodetectors based on Se/CsPbBr3 heterojunctions

“…Self-powered PDs can help solve this issue, as they not only demonstrate quick response rates and high photosensitivity under zero bias voltage, but can also efficiently separate electron hole pairs by means of a built-in electric field. 5,6 ZnO, SnO 2 , GaN, Ga 2 O 3 , and other wide band gap semiconductors are still the main building blocks for current mainstream selfpowered PDs with good photoelectric properties, [7][8][9][10][11][12][13][14][15][16][17][18][19] but these materials have drawbacks including high-temperature processing, difficult preparation procedures and high costs. 20,21 Therefore, it is necessary to fabricate stable and high-quality self-powered PDs using uncomplicated and inexpensive technologies methods to improve their responsivity and response time.…”