Optical and Electronic Properties of Femtosecond Laser-Induced Sulfur-Hyperdoped Silicon N+/P Photodiodes

Impurity-mediated near-infrared (NIR) photoresponse in silicon is of great interest for photovoltaics and photodetectors. In this paper, we have fabricated a series of n+/p photodetectors with hyperdoped silicon prepared by ion-implantation and femtosecond pulsed laser. These devices showed a remarkable enhancement on absorption and photoresponse at NIR wavelengths. The device fabricated with implantation dose of 1014 ions/cm2 has exhibited the best performance. The proposed method offers an approach to fabricate low-cost broadband silicon-based photodetectors

Genetic and molecular analysis of the anthocyanin pigmentation pathway in Epimedium

IntroductionFlower color is an ideal trait for studying the molecular basis for phenotypic variations in natural populations of species. Epimedium (Berberidaceae) species exhibit a wide range of flower colors resulting from the varied accumulation of anthocyanins and other pigments in their spur-like petals and petaloid sepals.MethodsIn this work, the anthocyanidins of eight different Epimedium species with different floral pigmentation phenotypes were analyzed using HPLC. Twelve genes involved in anthocyanin biosynthesis were cloned and sequenced, and their expression was quantified.ResultsThe expression levels of the catalytic enzyme genes DFR and ANS were significantly decreased in four species showing loss of floral pigmentation. Complementation of EsF3’H and EsDFR in corresponding Arabidopsis mutants together with overexpression of EsF3’5’H in wild type Arabidopsis analysis revealed that these genes were functional at the protein level, based on the accumulation of anthocyanin pigments.DiscussionThese results strongly suggest that transcriptional regulatory changes determine the loss of anthocyanins to be convergent in the floral tissue of Epimedium species

Assembly and phylogenetic analysis of the complete chloroplast genome sequence of Gentiana scabra Bunge

The first complete chloroplast (cp) genome of Gentiana scabra was determined from Illumina paired-end sequencing data in this study. The cp genome of G. scabra is 146,915 bp in length with 37.84% overall GC content, including a large single copy (LSC) region of 79,350 bp and a small single copy (SSC) region of 17,027 bp, which are separated by a pair of inverted repeats (IRs) of 25,269 bp. The cp genome is composed of 130 genes, including 85 protein-coding genes, 8 rRNA genes, and 37 tRNA genes. Phylogenetic analysis indicated that the G. scabra is more closely related to subfamily of Gentianoideae than Menyanthaceae

Photovoltage responses of graphene-Au heterojunctions

As an emerging 2D material, graphene’s several unique properties, such as high electron mobility, zero-bandgap and low density of states, present new opportunities for light detections. Here, we report on photovoltage responses of graphene-Au heterojunctions, which are made of monolayer graphene sheets atop Au electrodes designed as finger-shape and rectangle-shape, respectively. Besides confirming the critical role of space charge regions located at the graphene-Au boundary, photovoltage responses are measured in the visible to infrared spectral region with a cut-off wavelength at about 980 nm, which is likely imposed by the Pauli blocking of interband transition in the contact-doped graphene. The photoresponsivity is shown to decrease with increasing wavelength. A band diagram of the graphene-Au heterojunction is proposed to understand the photoresponse mechanism

Optical and Electronic Properties of Femtosecond Laser-Induced Sulfur-Hyperdoped Silicon N+/P Photodiodes

Abstract Impurity-mediated near-infrared (NIR) photoresponse in silicon is of great interest for photovoltaics and photodetectors. In this paper, we have fabricated a series of n+/p photodetectors with hyperdoped silicon prepared by ion-implantation and femtosecond pulsed laser. These devices showed a remarkable enhancement on absorption and photoresponse at NIR wavelengths. The device fabricated with implantation dose of 1014 ions/cm2 has exhibited the best performance. The proposed method offers an approach to fabricate low-cost broadband silicon-based photodetectors

Enhanced absorption of graphene with variable bandwidth in quarter-wavelength cavities

Quarter-wavelength cavity, as a classical structure for preventing wave reflection, presents an effective way to enhance the interaction between light and material of ultrathin thickness. In this paper, we propose a method to control the bandwidth of graphene’s enhanced absorption in quarter-wavelength cavity. By varying the spacing distance between graphene and a metallic reflecting plane, which equals to an odd number of quarter-wavelengths, fundamental and higher order cavity modes are excited, whose fields couple to graphene with different spectral bandwidths, leading to bandwidth-controllable absorption in graphene. Absorption efficiencies of 9% and 40% are measured for graphene monolayer at 15° and 85° incident angles, respectively. Its absorption bandwidth varies between 52% and 10% of the central wavelength when the spacing distance between graphene and metallic reflecting plane increases from a quarter wavelength to seven quarter wavelengths. Our findings pave a way in engineering graphene for strong absorption with a controllable bandwidth, which has potential applications in tailoring spectral response of graphene-based optoelectronic devices