Zeng Xi, Lontchi Jackson, Zhukova Maria, Bolt Pieter, Smor Marcel, Fourdrinier Lionel, Li Guoli, Flandre Denis
Opt Express. 2022 Apr 11;30(8):13875-13889. doi: 10.1364/OE.456352.
An ultra-thin CdS/CIGS heterojunction photodiode fabricated on steel firstly exhibits dual-mode broadband photodetection from ultraviolet to near infrared spectrum. In the photovoltaic mode, the CIGS photodiode, working as a self-driven photodetector, shows an outstanding photodetection capability (under a light power density of 20 µW cm at 680 nm), reaching a record detectivity of ∼4.4×10 Jones, a low noise equivalent power (NEP) of 0.16 pW Hz and a high Ilight/Idark ratio of ∼10, but a relatively low responsivity of ∼0.39 A W and an external quantum efficiency (EQE) of ∼71%. Working under the same illumination but in the photoconductive mode (1 V reverse bias), the responsivity and EQE are significantly enhanced to 1.24 A W and 226%, respectively, but with a relatively low detectivity of 7×10 Jones and a higher NEP of 10.1 pW Hz. To explain these results, a corrected photoconductive gain (G) model indicates that minority electrons could be localized in the defects, surface states and depletion region of the CIGS photodiode, causing excess hole accumulation in the ultra-thin CIGS photodiode and thus high EQE over 100% (G over 1).
首次在钢上制备的超薄硫化镉/铜铟镓硒（CdS/CIGS）异质结光电二极管展现出从紫外到近红外光谱的双模宽带光电探测能力。在光伏模式下，作为自驱动光电探测器的CIGS光电二极管表现出卓越的光电探测能力（在680nm处光功率密度为20μW/cm²时），达到约4.4×10¹²Jones的创纪录探测率、0.16pW/Hz的低噪声等效功率（NEP）和约10的高光暗电流比，但响应度相对较低，约为0.39A/W，外部量子效率（EQE）约为71%。在相同光照下但处于光电导模式（1V反向偏压）时，响应度和EQE分别显著提高到1.24A/W和226%，但探测率相对较低，为7×10¹¹Jones，NEP较高，为10.1pW/Hz。为了解释这些结果，一个修正的光电导增益（G）模型表明，少数载流子电子可能会局域在CIGS光电二极管的缺陷、表面态和耗尽区中，导致超薄CIGS光电二极管中出现过量空穴积累，从而使EQE超过1（G超过1）。
