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Interface Defect Engineering for Improved Graphene-Oxide-Semiconductor Junction Photodetectors

ACS Applied Nano Materials

Ruiz, Isaac R.; Laros, James H.; Smith, Sean S.; Dickens, Peter D.; Paisley, Elizabeth A.; Shank, Joshua S.; Howell, Stephen W.; Sarma, Raktim S.; Draper, Bruce L.; Goldflam, Michael G.

The deeply depleted graphene-oxide-semiconductor (D2GOS) junction detector provides an effective architecture for photodetection, enabling direct readout of photogenerated charge. Because of an inherent gain mechanism proportional to graphene's high mobility (μ), this detector architecture exhibits large responsivities and signal-to-noise ratios (SNR). The ultimate sensitivity of the D2GOS junction detector may be limited, however, because of the generation of dark charge originating from interface states at the semiconductor/dielectric junction. Here, we examine the performance limitations caused by dark charge and demonstrate its mitigation via the creation of low interface defect junctions enabled by surface passivation. The resulting devices exhibit responsivities exceeding 10 000 A/W - a value which is 10× greater than that of analogous devices without the passivating thermal oxide. With cooling of the detector, the responsivity further increases to over 25 000 A/W, underscoring the impact of surface generation on performance and thus the necessity of minimizing interfacial defects for this class of photodetector.

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TYPE Journal Article YEAR 2019
DOIOSTIScopus

Topological Quantum Materials for Quantum Computation

Nenoff, T.M.; Chou, Stanley S.; Dickens, Peter D.; Modine, N.A.; Yu, Wenlong; Lee, Stephen R.; Sapkota, Keshab R.; Wang, George T.; Wendt, J.R.; Medlin, Douglas L.; Leonard, Francois L.; Pan, Wei P.

Recent years have seen an explosion in research efforts discovering and understanding novel electronic and optical properties of topological quantum materials (TQMs). In this LDRD, a synergistic effort of materials growth, characterization, electrical-magneto-optical measurements, combined with density functional theory and modeling has been established to address the unique properties of TQMs. Particularly, we have carried out extensive studies in search for Majorana fermions (MFs) in TQMs for topological quantum computation. Moreover, we have focused on three important science questions. 1) How can we controllably tune the properties of TQMs to make them suitable for quantum information applications? 2) What materials parameters are most important for successfully observing MFs in TQMs? 3) Can the physical properties of TQMs be tailored by topological band engineering? Results obtained in this LDRD not only deepen our current knowledge in fundamental quantum physics but also hold great promise for advanced electronic/photonic applications in information technologies.

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TYPE SAND Report YEAR 2019
DOIOSTI
11 Results
11 Results