Browsing by Subject "Hot electron"

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    Plasmonically enhanced hot electorn based optoelectronic devices
    (2015-06) Atar, Fatih Bilge
    Hot electron based optoelectronic devices have been regarded as cost-e ective candidates to their conventional counterparts. The efficiency of conventional optoelectronic devices that rely on semiconductor photo-absorbers are mainly limited by the energy bandgap of the semiconductor. On the other hand, hot electron devices can overcome this limitation via the \internal photoemission" mechanism. Absorbed photons give their energy to free electrons of the metal and these high energy (\hot") electrons can be used to generate photocurrent in proper device configurations. High optical re ection from metals has remained as the main drawback of this photocurrent generation scheme but this problem has recently been addressed by the use of surface plasmons. Optical energy can be tightly confined to a metal layer or metal nanostructures in the form of surface plasmons, and the decay of surface plasmons in metals generates hot electrons. In this work, we study mechanisms of surface plasmon excitation, surface plasmon decay, hot electron generation and hot electron photoemission for photocurrent generation. We demonstrate novel device architectures and plasmon excitation structures. We demonstrate the use of such layers for plasmon enhanced hot electron based photodetectors and photovoltaic devices. A metal-semiconductor Schottky junction diode structure is used as hot electron photodetector. A double metal-insulator-metal (MIM) architecture is proposed as a hot electron photovoltaic device. Full wave electromagnetic simulations of these device structures are conducted to provide insight into the surface plasmon assisted hot electron generation process and give future directions in this field.
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    ItemOpen Access
    Semiconductor-less photovoltaic device
    (IEEE, 2013) Atar, Fatih B.; Battal, Enes; Aygun, Levent E.; Dağlar, Bihter; Bayındır, Mehmet; Okyay, Ali Kemal
    We demonstrate a novel semiconductor-less photovoltaic device and investigate the plasmonic effects on this device structure. The device is made of metal and dielectric layers and the operation is based on hot carrier collection. We present the use of surface plasmons to improve energy conversion efficiency. The field localization provided by surface plasmons confine the incident light in the metal layer, increasing the optical absorption and hot electron generation rate inside the metal layer. The device consists of two tandem MIM (metal-insulator-metal) junctions. Bottom MIM junction acts as a rectifying diode and top MIM junction is used to excite surface plasmons. The device operation principle as well as the topology will be discussed in detail. © 2013 IEEE.