We demonstrate an intrinsically fast, Seebeck-type metal-semimetal-metal infrared photodetector based on Cd 3 As 2 crystals. The Seebeck voltage is induced under off-center illumination, leading to asymmetric temperature gradients and net current flow.The sensor's room-temperature responsivity is 0.27 mA/W. The photocurrent signal is readily registered at a modulation frequency of 6 kHz, and the sensor's intrinsic bandwidth is predicted to approach terahertz. We find that the photocurrent depends on the optical power and modulation frequency. Our study reveals crystalline Cd 3 As 2 as a promising material for high-bandwidth and spectrally broad photo-sensing, imaging, and communication.

This study presents a facile high‐yield bottom‐up fabrication and morphology‐structure investigations of a free‐standing network of multi‐layer quasi‐2D flakes consisting of intrinsically nonlayered γ‐Al2O3. The synthesis comprises a multi‐cycle atomic layer deposition (ALD) of amorphous alumina that uses an interconnected graphene network as a growth scaffold followed by ≈800 °C air anneal. The structures are studied by X‐ray diffraction, selected area electron diffraction, and high‐resolution transmission electron microscopy, while electric properties are assessed with the help of two‐terminal dc‐transport measurements. The individual flakes comprise nanocrystalline phase cubic spinel γ‐Al2O3 with a close‐packed cubic texture in the 〈111〉cubic ALD‐induced growth direction. The charge transport is confirmed to be Ohmic with the room temperature electrical conductivity approaching ≈10−8 S m−1. This work opens a door to a low‐cost highly scalable synthesis of a variety of quasi‐2D metal oxides for widespread uses ranging from support material, sensing to environmental remediation.

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This study traces the early developments of the concept of experiment with a view of extending the subject in both content and approach. It extends the content of the subject slightly backward, prior to the methodological breakthroughs of the Optics of Ibn al-Haytham (Alhazen or Alhacen, d. ca. 1040), which are credited as a "significant landmark in the history of experimental science." And it extends the approach to the subject slightly forward, from the premise that early science was "largely carried out in books," to a close examination of the books through which the footprints of'experiment' may be traced. The point of departure is the Optics of Ahmad ibn 'Isă, a revealing text for the early developments of concepts such as 'demonstration' and 'experiment', and one through which some modern discussions are examined and extended with reference to this and other historical sources.

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