................................................................................................................................... ii Dedication................................................................................................................................ iv Acknowledgments.................................................................................................................... v Vita........................................................................................................................................... vii List of Tables............................................................................................................................. xii List of Figures............................................................................................................................ xiv Chapter 1 ‐ Introduction........................................................................................................... 1 1.1 ‐ Microbial fuel cells.................................................................................................. 2 1.2 ‐ Microbial fuel cell applications............................................................................... 4 1.3 ‐ Research problems associated with MFC technology............................................. 5 1.4 ‐ Introduction to this research study......................................................................... 6 Chapter 2 ‐ Effects of Nano‐structure Enhanced Cathodes on Electricity Production of Two‐ Chamber Microbial Fuel Cells 2.1 ‐ Introduction............................................................................................................ 8 2.2 ‐ Materials and Methods........................................................................................... 16 2.2.1 ‐ Electrode construction Graphite bar anodes.......................................................................................... 18 Graphite bar cathodes....................................................................................... 20

In Partial Fulfillment of the Requirements for the Degree of

InAs/(In,Ga)Sb type-II strained layer superlattices (T2SLs) have made significant progress since they were first proposed as an infrared (IR) sensing material more than three decades ago. Numerous theoretically predicted advantages that T2SL offers over present-day detection technologies, heterojunction engineering capabilities, and technological preferences make T2SL technology promising candidate for the realization of high performance IR imagers. Despite concentrated efforts of many research groups, the T2SLs have not revealed full potential yet. This paper attempts to provide a comprehensive review of the current status of T2SL detectors and discusses origins of T2SL device performance degradation, in particular, surface and bulk dark-current components. Various approaches of dark current reduction with their pros and cons are presented.

/pdf/inas-gasb-type-ii-superlattice-detectors-a5m5m0wdca.pdf

InAs/GaSb Type-II Superlattice Detectors

Detailed performance model of a hybrid photovoltaic/thermal system utilizing selective spectral nanofluid absorption

Carbon-based organic electronics are a technology, with the potential of complementing and substituting opto-electronic devices based on inorganic semiconductors and metals. In the group of organic semiconductors, carbon allotropes come with outstanding opto-electric properties and are remarkable candidates for novel applications like printed electronics via solution-processing on mechanically flexible, robust and light weight substrates, while reducing the environmental impact. Carbon allotropes like fullerenes, graphene quantum dots (GQD), carbon nanotubes (CNT), graphene and also diamond are especially interesting for photodetectors due to their tunable bandgap, high absorption coefficients and high charge carrier mobilites. These unique opto-electric properties of the allotropes, which strongly depend on their molecular dimensionality (0D, 1D, 2D and 3D), allow each allotrope to be used in a preferential range. Hence, relying on the intrinsic properties of carbon allotropes or by hybridization, carbon-based photodetectors are built for a spectral bandwidth, reaching from gamma-rays to THz radiation. This review highlights the recent advances in photodetectors based on fullerenes, GQDs, CNTs, graphene and diamond, with the focus on room temperature-operated devices. The versatility of multi-dimensional carbon allotropes is outstanding, and promising results outline the maturing of all carbon-based photodetection across the technologically relevant wavelengths.

/pdf/carbon-photodetectors-the-versatility-of-carbon-allotropes-49m7c0ymm3.pdf

Carbon Photodetectors: The Versatility of Carbon Allotropes

The InSb photodetector on a Si substrate acts as a signal receiver for the mid-infrared silicon photonics application to overcome the limitation of group IV semiconductors In this paper, we demonstrated an InSb p–i–n photodetector with an InAlSb barrier layer grown on (100) silicon substrates via a GaAs/Ge buffer by molecular beam epitaxy The lattice mismatch between InSb and GaAs was accommodated by an interfacial misfit array The 50% cutoff detectable wavelength of this detector increased from 57 μm at 80 K to 63 μm at 200 K An 80 K detectivity of 88 × 109 cmHz1/2 W–1 at 53 μm was achieved with a quantum efficiency of 163% The dark current generating mechanism of this detector is both generation–recombination and surface leakage above 140 K, while it is only surface leakage from 120 to 40 K

https://dr.ntu.edu.sg/bitstream/10356/80650/1/Monolithic%20Integration%20of%20InSb%20Photodetector%20on%20Silicon%20for%20Mid-Infrared%20Silicon%20Photonics.pdf

Monolithic Integration of InSb Photodetector on Silicon for Mid-Infrared Silicon Photonics

Temperature dependence of the energy bandgap of HgInTe

Empirical expression for the composition and temperature dependence of the energy gap in InAlSb

One of the major challenges faced by antimonide-based devices is a result of the large number of surface states that are generated. Surface passivation and subsequent capping of the surfaces are essential for any practical applicability of this material system, as evidenced by the comparison of unpassivated and passivated InAs/GaSb superlattice mid-infrared photodiodes herein. The surface passivation methods include silicon dioxide (SiO2) coating after anodic sulfide, SiO2 coating after anodic oxide, SiO2 coating only, zinc sulfide (ZnS) coating after anodic sulfide, and ZnS coating after ammonium sulfide [(NH4)2S] chemical passivation. The leakage current as a function of bias voltage (I–V) for superlattice diodes obtained using different passivation methods has been examined at 77 K. The best performance was demonstrated by the SiO2 after anodic sulfide passivation. The leakage current of the passivated diode is four orders of magnitudes less than that of the unpassivated diode.

Passivation of InAs/GaSb type II superlattice photodiodes

Growth and electrical characterization of type II InAs/GaSb superlattices for midwave infrared detection

One of the major challenges of antimonide-based devices arises owing to the large number of surface states generated during fabrication processes. Surface passivation and subsequent capping of the surfaces are absolutely essential for any practical applicability of this material system. In this paper, we proposed a new passivation method (zinc sulfide coating after anodic fluoride) for InAs/GaSb superlattice infrared detectors. InAs/GaSb superlattice short-wavelength infrared materials were grown by molecular beam epitaxy on GaSb (100) substrates. A GaSb buffer layer, which can decrease the occurrence of defects with similar pyramidal structure, was grown for optimized superlattice growth condition. High resolution X-ray diffraction indicated that the period of the superlattice corresponding to fourth satellite peak was 39.77 A. The atomic force microscopy images show the roughness was below 1.7 nm. The result of photoresponse spectra shows that the cutoff wavelength was 3.05 μm at 300 K.

Weiguo Sun

Papers

Temperature dependence of the energy bandgap of HgInTe

Empirical expression for the composition and temperature dependence of the energy gap in InAlSb

Passivation of InAs/GaSb type II superlattice photodiodes

Growth and electrical characterization of type II InAs/GaSb superlattices for midwave infrared detection

Anodic fluoride passivation of type II InAs/GaSb superlattice for short-wavelength infrared detector