Papers by Keyword: P-N Junction

Abstract: Different procedures of laser-induced doping of the surface region of semi-insulating CdTe semiconductor are discussed. CdTe crystals pre-coated with an In dopant film were subjected to irradiation with nanosecond laser pulses in different environments (vacuum, gas or water). The dopant self-compensation phenomenon was overcome under laser action and In impurity with high concentration was introduced in a thin surface layer of CdTe. In the case of a thick (300-400 nm) In dopant film, laser-induced shock wave action has been considered as the mechanism of solid-phase doping. Formed In/CdTe/Au diode structures showed high rectification depending on the fabrication procedure. Diodes with low leakage current were sensitive to high energy radiation.

Abstract: P-N junction photocatalyst NiO/TiO2 photoexcited by visible light was prepared by sol-gel method using Ni(NO3)2•6H2O and tetrabutyl titanate [Ti(OC4H9)4] as the raw materials. The p-n junction photocatalyst NiO/TiO2 was characterized by UV-Vis diffuse reflection spectrum, fluorescence spectra (FL), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). UV-Vis spectrum showed that the absorption wavelength range of NiO/TiO2 is extended to the visible region, making it an effective photocatalyst photoexcited by visible light. This was demonstrated by photocatalytic reduction of Cr2O72- and photocatalytic oxidation of methyl orange (MO) under visible-light (λ>400 nm) irradiation. Doped-NiO effectively suppressed the phase transformation of anatase to rutile and the growth of titania crystallites. The optimum percentage of doped NiO is 0.5% (mole ratio of Ni/Ti). Effects of heat treatment on the photocatalytic activity of p-n junction photocatalyst NiO/TiO2 were investigated. The mechanisms of influence on the photocatalytic activity were also discussed by the p-n junction principle.

Abstract: We report the poly(3iophene) (P3HT)/ZnO nanobelt hybrid p-n junction diodes characterized by using a conductive atomic force microscope (C-AFM). The diodes exhibited a turn-on voltage of about 2.5 V and ideality factor of about 11.6. The obvious current steps in the I-V characteristics under the reverse bias were clearly observed at room temperature. The origin of these steps is suggested to be attributed to the charge injection-trapping induced by nanoparticles on the surface of the ZnO nanobelt.

Abstract: The characteristics of boron diffusion in 3C-SiC at low temperature have been measured using spreading resistance technique and electroluminescence spectroscopy. The coefficient of boron diffusion in the temperature range of 1150 –1250°С has been found to be about 5.5 x 10-11–5.0 x 10-10 cm2/sec and the activation energy of boron diffusion was determined to be about 0.9 –1.15 eV. Electroluminescence spectra of 3C-SiC p-n junction structures showed peaks at 750 and 630 nm due to growth defects and carbon-silicon divacancies respectively.

Abstract: The total leakage current in silicon p-n junction diodes compatible with 0.8 µm CMOS technology is investigated. The generation lifetime is a key parameter for the leakage current, which can be obtained from the current-voltage (I-V) and the capacitance-voltage (C-V) characteristics. As will be shown, the electrically active defect from ion implantation process generated in p-n junction can be extracted from the generation current density.

Abstract: This paper presents the relation between the staring cobalt thickness with carrier generation lifetime, which effects to the sensitivity of p-n junction temperature sensor. The starting cobalt thickness of 12, 20 and 30nm have been used. The carrier generation lifetimes have been calculated from the reverse current-voltage (I-V) characteristics. The highest carrier generation lifetime has been obtained in the case of 12nm starting cobalt thickness. The highest sensitivity of p-n junction temperature sensor has also been observed from the case of 12nm starting cobalt thickness. The sensitivity has been calculated from the relation between leakage current versus temperature. The sensitivity of p-n junction temperature sensor can be improved by increasing carrier generation lifetime.

Abstract: Position-sensitive photodetectors, a useful class of sensor with a wide range of applications in automatization and measuring techniques, on the basis of a La0.7Sr0.3MnO3/Si heterojunction have been developed. Thin p-La0.7Sr0.3MnO3 films were grown on n-Si substrates by laser molecular beam epitaxy. The large lateral photovoltaic effect has been observed in response to excitation by ultraviolet laser spot irradiation. The position characteristics are symmetric to the zero and linear between the contacts. The devices work well under unbiased conditions and so are simple to configure for practical applications.

Abstract: The polyaniline (PANI) coated titania (TiO2) has been prepared with ammonium persulfate (APS) as an oxidant in sodium dodecylsulfate(SDS) micellar aqueous solution. These nanosized powders could transfer into the organic phase. With increase in the amount of SDS, the dispersibility into the organic solvent was increased. Consequently, the electrical conductivity of the product was also decreased. The obtained composites showed 14.16 S/cm of conductivity at maximum while the value was almost independent on the polyaniline coating ratio in range of 100~20wt%. The conductivity value of composite with 20wt% polyaniline was 70000 times higher than that of raw titania. Modified titania had properties of polyaniline and titania together. In addition these composite showed the photoconductive response against the UV irradiation, which might show the existence of P-N junction between titania and polyaniline. The detailed structure and property analyses with X-ray, UV-spectroscopy, electron microscopy and so on will be discussed in relation to the synthetic conditions

Abstract: A betavoltaic cell in 4H SiC is demonstrated. An abrupt p-n diode structure was used to collect the charge from a 1mCi Ni-63 source. An open circuit voltage of 0.95V and a short circuit current density of 8.8 nA/cm2 were measured in a single p-n junction. An efficiency of 3.7% was obtained. A simple photovoltaic type model was used to explain the results. Good correspondence with the model was obtained. Fill factor and backscattering effects were included. Efficiency was limited by edge recombination and poor fill factor.

Abstract: This paper reports on initial fabrication and electrical characterization of 3C-SiC p+n junction diodes grown on step-free 4H-SiC mesas. Diodes with n-blocking-layer doping ranging from ~ 2 x 1016 cm-3 to ~ 5 x 1017 cm-3 were fabricated and tested. No optimization of junction edge termination or ohmic contacts was employed. Room temperature reverse characteristics of the best devices show excellent low-leakage behavior, below previous 3C-SiC devices produced by other growth techniques, until the onset of a sharp breakdown knee. The resulting estimated breakdown field of 3C-SiC is at least twice the breakdown field of silicon, but is only around half the breakdown field of <0001> 4H-SiC for the doping range studied. Initial high current stressing of 3C diodes at 100 A/cm2 for more than 20 hours resulted in less than 50 mV change in ~ 3 V forward voltage.