Silicon Nanowire Arrays with Nitrogen-Doped Graphene Quantum Dots for Photodetectors

Abstract

A significantly improved silicon nanowire (SiNW)based broadband photodetector is obtained in this work using the core−shell structure of SiNWs with hydrothermally processed nitrogen doped graphene quantum dots (N-GQDs). The performance of the photodetector device is enhanced significantly by enlarging the effective surface area of the SiNW/N-GQD heterostructure by controlled KOH etching of SiNWs. In combination with SiNWs, low-cost hydrothermal processed N-GQDs are used as a light absorber in the UV region and also as an emitter in the visible region which is reabsorbed by the SiNWs to enhance the device performance. The SiNW/N-GQD heterostructure photodetector exhibits a large photocurrent to dark-current ratio (∼0.8 × 10 2 under zero bias and as high as ∼0.5 × 10 4 under −2 V bias for 2 min KOH etching), remarkably low dark current (∼55 nA under −2 V bias for 2 min KOH etching and is six orders lower compared to control SiNWs device), and significantly improved external quantum efficiency (EQE) exceeding 150% in the near IR and ∼500% at 460 nm wavelength in the visible region. Such higher EQE may arise due to the (i) enhanced optical absorption, (ii) suppressed dark current, (iii) photomultiplication of charge carriers because of the presence of trap states, and (iv) improved carrier transport and collection efficiency due to core−shell structure and nanoscale morphology control. It is expected that the reported SiNWs/N-GQDs core−shell heterostructure device might be useful for high-performance optoelectronic applications in the near future.

Research progress of silicon nanowires array photodetectors

“…[66] 2021 年，Mao 等人 [68] [67] Figure 7 Schematic diagram of gate-free photodetector based on MoS 2 /Ag-NP/Si-NW heterostructure and the characteristics of its responsivity vs. incident light power density. [67] 4.4 半导体异质结对 Si-NW 阵列光电探测器性能的提升 2014 年，Luo 等人 [69] 报道了通过在硅纳米线表面装饰碳量子点来制造硅纳米线/ 碳量子点的"核/壳"结构异质结自驱动、宽谱光电探测器，该器件具有高"开/关" 电流比及快速响应时间。这主要归因于以下几个方面： (1)硅和碳量子点之间形成 的异质结加速了电荷分离与转移。 (2)三维"核/壳"结构增加了硅纳米线与碳量子 点的接触面积，且这种接触界面允许在近距离内实现电荷分离及扩散，从而提高了 载流子的收集效率。 图 8 Si-NW/N-GQD 异质结构器件的光生载流子产生机制及传输机理示意图 [70] Figure 8 Schematic diagram of photogenerated carriers generation mechanism and their transmission mechanism for Si-NW/N-GQD heterostructure devices. [70] 2021 年 ，Mondal 等 人 [70] [71] 通过在化学蚀刻的垂直排列的 Si-NW 上沉积 CdS 纳米 颗粒制备异质结 Si-NW/CdS 光电探测器。在近红外(NIR)区域观察到其"明/暗" 电流比为 6.7。在 8mW/cm 2 的 900nm 近红外光照射下，其响应率和比探测率分别为 821 mA/W 和 1.21×10 12 Jones。 图 9 Si-NW/Cs 3 Cu 2 I 5 纳米晶异质结光电探测器 [71] Figure 9 Photodetector based on Si-NW/Cs 3 Cu 2 I 5 nanocrystalline heterojunction.…”

“…[67] 4.4 半导体异质结对 Si-NW 阵列光电探测器性能的提升 2014 年，Luo 等人 [69] 报道了通过在硅纳米线表面装饰碳量子点来制造硅纳米线/ 碳量子点的"核/壳"结构异质结自驱动、宽谱光电探测器，该器件具有高"开/关" 电流比及快速响应时间。这主要归因于以下几个方面： (1)硅和碳量子点之间形成 的异质结加速了电荷分离与转移。 (2)三维"核/壳"结构增加了硅纳米线与碳量子 点的接触面积，且这种接触界面允许在近距离内实现电荷分离及扩散，从而提高了 载流子的收集效率。 图 8 Si-NW/N-GQD 异质结构器件的光生载流子产生机制及传输机理示意图 [70] Figure 8 Schematic diagram of photogenerated carriers generation mechanism and their transmission mechanism for Si-NW/N-GQD heterostructure devices. [70] 2021 年 ，Mondal 等 人 [70] [71] 通过在化学蚀刻的垂直排列的 Si-NW 上沉积 CdS 纳米 颗粒制备异质结 Si-NW/CdS 光电探测器。在近红外(NIR)区域观察到其"明/暗" 电流比为 6.7。在 8mW/cm 2 的 900nm 近红外光照射下，其响应率和比探测率分别为 821 mA/W 和 1.21×10 12 Jones。 图 9 Si-NW/Cs 3 Cu 2 I 5 纳米晶异质结光电探测器 [71] Figure 9 Photodetector based on Si-NW/Cs 3 Cu 2 I 5 nanocrystalline heterojunction. [71] 2021 年，Liang 等人 [72] 2021 年，Feng 等人 [73] 提出了一种新型肖特基势垒光伏探测器，该探测器采用石 墨烯单层覆盖硅纳米柱阵列的结构。与没有石墨烯层的传统探测器相比，在覆盖可 见光到近红外波长(450~1100nm)的情况下及在−0.4 V 偏压下有较低的漏电流 (∼0.97 mA) 、高的比探测率(1.43×10 13 Jones)和响应率(10 6 V/W) ，这使其成为具 有高灵敏度宽谱成像的、适用于弱信号检测的探测器件。 2021 年，Tong 等人 [74] 制造了一种高灵敏度的 Si-NP/PtTe 2 "核/壳"异质结光电 探测器。在±1V 的偏压下，该器件表现出显著的整流效果，其整流比为 6.0×10 3 。此 外，其响应率、比探测率和外量子效率为 0.78A/W、3.09×10 11 [81] Figure 10 Preparation process (a) and device configuration (b), energy level diagram (c) and SEM photos of the interdigital channels (d) for the Si-NW/perovskite heterojunction photodetector.…”

Hybrid UV Photodetector Design Incorporating AuPt Alloy Hybrid Nanoparticles, ZnO Quantum Dots, and Graphene Quantum Dots

“…16,17 As a result, the GQD-based PDs have demonstrated excellent optoelectronic performance. For example, a high on/off ratio of 80 and over 500% EQE were reported based on the Si-N-GQD PD 18 and the incorporation of GQD in the metal NP/TiO 2 nanostructure showed over one-order improvement in photocurrent. 3 At the same time, noble metal nanoparticles (NPs) are extensively explored as an active element for the hybrid PD component as they can provide strong absorption, scatting, and local e-field enhancement via localized surface plasmonic resonance (LSPR).…”

“…Meanwhile, graphene quantum dot (GQDs) are attracting tremendous interest as a hybrid PD component in recent years due to their high photocarrier generation nature through multiple free carrier excitation, thin layer configuration, and thermal stability. , As a result, the GQD-based PDs have demonstrated excellent optoelectronic performance. For example, a high on/off ratio of 80 and over 500% EQE were reported based on the Si-N-GQD PD and the incorporation of GQD in the metal NP/TiO 2 nanostructure showed over one-order improvement in photocurrent . At the same time, noble metal nanoparticles (NPs) are extensively explored as an active element for the hybrid PD component as they can provide strong absorption, scatting, and local e-field enhancement via localized surface plasmonic resonance (LSPR). , To date, Ag and Au NPs have been widely explored in a variety of optical applications due to their intense dipolar and quadrupolar resonance modes in the collective oscillation, which can effectively generate hot electrons in the vicinity of NPs .…”

Remarkable Noise Reduction in High-Stability Self-Powered Doped Graphene/Si-Quantum Dot Broadband Photodetectors by Using Graphene Quantum Dots as an Interlayer

“…Nevertheless, the photoresponse is limited in its further enhancement owing to the large leakage current caused by relatively high-density defect states at the GR/Si interface . To overcome this problem, many researchers have made a lot of efforts to improve the performance by giving varieties to the basic structure of the GR/Si heterojunction. − Si quantum dots (SiQDs)-embedded SiO 2 (SiQDs:SiO 2 ) has been highly attractive for photonic device applications, thanks to distinctive properties such as stronger light absorption and faster photo-sensing than bulk Si. Particularly, SiQDs:SiO 2 was well applied in solar cells and PDs. − The optoelectronic properties of the GR/Si heterojunction proved to be improved by employing SiQDs:SiO 2 between GR and a Si wafer in previous studies, ,− resulting from the improvement of the band profiles at the GR/Si interface.…”