Andrew and Erna Viterbi Faculty of Electrical Engineering, Technion , Haifa 3200003, Israel.
Nano Lett. 2018 Jan 10;18(1):190-201. doi: 10.1021/acs.nanolett.7b03873. Epub 2017 Dec 11.
Silicon-based photodetectors cannot distinguish between different wavelengths. Therefore, these detectors relay on color-specific filters to achieve color separation. Color filters add complexity to color sensitive device fabrication, and hinder miniaturization of such devices. Here, we report an ultrasmall (as small as ∼20 nm by 300 nm), red-green-blue-violet (RGBV) filter-free spectrally gated field effect transistor (SGFET) detectors. These photodetectors are based on organic-silicon nanowire hybrid FET devices, capable of detecting specific visible wavelength spectrum with full width at half-maxima (fwhm) under 100 nm. Each SGFET is controlled by a distinctive RGBV spectral range, according to its specific organic fluorophore functionalization. The spectral-specific RGBV detection is accomplished via covalent attachment of different fluorophores. The fluorophore molecules inject electrons into the nanowire structure as a result of light absorption at the appropriate RGBV spectral range. These photoinduced electrons modify the occupancies of the oxide's surface states, shifting the device threshold voltage, thus changing its conductivity, and functioning as a negative stress bias in a p-type SiNW FETs. A positive biasing can be achieved via UV light-induced ionization, which leads to detrapping and translocation of electrons at the oxide layer. Furthermore, a novel theoretical model on the mechanism of action of these devices was developed. Also, we show that suspended SGFETs can function as nonvolatile memory elements, which unlike fast-relaxing on-surface SGFETs, can store discrete "on" (RGBV illumination) and "off" (UV illumination) states for several days at ambient conditions. We also demonstrate a unique single-nanowire multicolor photodetector, enabling in principle a broad spectral detection over a single silicon nanowire element. These highly compact, spectral-controlled nanodevices have the potential to serve in various future novel optoelectric applications.
基于硅的光电探测器无法区分不同的波长。因此，这些探测器依赖于特定颜色的滤波器来实现颜色分离。颜色滤波器增加了彩色敏感设备制造的复杂性，并阻碍了这些设备的小型化。在这里，我们报告了一种超小型（小至约 20nm×300nm）的红-绿-蓝-紫（RGBV）无滤光片光谱门控场效应晶体管（SGFET）探测器。这些光电探测器基于有机-硅纳米线混合 FET 器件，能够以全宽半最大值（fwhm）小于 100nm 的方式检测特定的可见波长光谱。每个 SGFET 都由独特的 RGBV 光谱范围控制，这是根据其特定的有机荧光团功能化实现的。通过共价键合不同的荧光团来实现光谱特异性的 RGBV 检测。荧光团分子在适当的 RGBV 光谱范围内吸收光后，将电子注入纳米线结构中。这些光诱导电子修饰了氧化物表面态的占据，从而改变了器件的阈值电压，从而改变了其电导率，并在 p 型 SiNW FET 中作为负偏压工作。通过紫外光诱导的电离可以实现正偏压，这会导致电子在氧化物层中的脱陷和迁移。此外，还开发了一种关于这些器件作用机制的新理论模型。此外，我们还展示了悬浮 SGFET 可以作为非易失性存储元件，与快速弛豫的表面 SGFET 不同，它们可以在环境条件下存储离散的“开”（RGBV 光照）和“关”（UV 光照）状态数天。我们还展示了一种独特的单纳米线多色光电探测器，它原则上可以在单个硅纳米线元件上实现广泛的光谱检测。这些高度紧凑、光谱可控的纳米器件有可能在未来的各种新型光电应用中发挥作用。
