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    Effects of Si nanowire on the device properties of n-ZnSe/p-Si heterostructure
    (Springer, 2019) Coskun, E.; Gullu, H. H.; Colakoglu, T.; Emir, C.; Bozdogan, E.; Parlak, M.
    The semiconductor nanowire (NW) technology has raised attention owing to its one-dimensional geometry as a solution for lattice mismatch in the fabricated heterostructures. Although, SiNWs have been investigated for various device technologies, there is no published work on the p-n junction formed by deposition of ZnSe thin film on these NW structures, in which this film layer has significant optical and electrical properties in optoelectronics applications. The aim of this study is determining the device properties of n-ZnSe/SiNW heterojunction and obtaining the enhancement in the device application of the NW structure on Si surface with comparing to planar surface. SiNW was produced by metal assisted etching method as a cost-efficient process, and the ZnSe film was deposited on SiNW and planar Si substrates by thermal evaporation of elemental sources. The optical band gap of the deposited ZnSe film was determined as 2.7eV which is in a good agreement with literature. The ideality factor and series resistance values of the ZnSe/SiNW and ZnSe/Si heterojunctions were calculated as 3.12, 461 , and 4.52, 7.26x103, respectively. As a result of utilizing SiNW structure, a spectacular improvement in terms of the physical parameters related to device properties was achieved.
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    Improvement of electrical characteristics of SnSe/Si heterostructure by integration of Si nanowires
    (Elsevier B.V., 2021) Coşkun, Emre; Güllü, H. H.; Emir, C.; Parlak, M.
    In this study, the effects of the nanowire geometry on Si wafer substrate were investigated for the SnSe/Si-nanowire heterojunction device and the obtained results were compared with the one fabricated on planar Si surface. Nanowires on Si surface were produced by metal-assisted etching method and the SnSe film layer was deposited by thermal evaporation technique. On both Si and glass surfaces, deposited film shows polycrystalline and single SnSe phase. From optical transmission measurements, optical band gap of this film was determined as 1.36 eV in a good agreement with the literature. All SnSe/Si heterostructures were found in a p-n diode behavior and the ideality factor and series resistance values were calculated as 2.40, 547 Ω, and 3.71, 1.57 × 103 Ω, for SnSe/Si-nanowire and SnSe/Si heterojunctions, respectively. As a result, an improvement in device characteristics concerning the planar Si structure was found by utilizing Si nanowire structure.
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    Persimmon (Diospyros kaki l.) and johnsongrass [sorghum halepense (l.) pers.] are new natural hosts of peach latent mosaic viroid
    (Corvinus University of Budapest, 2021) Oksal, H. D.; Aydın, S.; Baran, M.; Emir, C.; Karanfil, A.; Bozdoğan, O.; Sipahioğlu, H. M.
    Peach latent mosaic viroid (PLMVd) naturally infects stone fruits worldwide. Here, we report the first detection of PLMVd in persimmon (Diospyros kaki L.) and a weed Johnsongrass [Sorghum halepense (L.) Pers.]. Samples corresponding to 12 persimmon specimens and weeds nearby the persimmon trees were collected from a germplasm collection plot in Malatya (Turkey). Total RNAs were isolated using a silica-based method and the complete viroid genome was amplified by reverse transcriptase polymerase chain reaction (RT-PCR). From these samples, PLMVd was detected in 7 of the 12 persimmons and in Johnsongrass revealing 8 new sequence variants. Multiple alignment and phylogenetic analyses revealed that identified persimmon and Johnsongrass isolates clustered only with PLMVd-walnut isolates previously identified from same locality. The nucleotide sequences of PLMVd persimmon and Johnsongrass isolates showed 96.71-99.11% similarity with the PLMVd isolates detected in different fruit crops in the world. A single specific mutation identified in two PLMVd persimmon variants (-TH2 and-TH10) effectively changed the predicted secondary structure of the agent. The identification and the genetic analyses of PLMVd variants in persimmon and Johnsongrass confirm that the agent is a ubiquitous and genetically variable viroid that infects many cultivated fruit crops and weeds worldwide.