4H-SiC P+N UV Photodiodes: Influence of Temperature and Irradiation
TL;DR: In this article, the p+n photodiodes based on ultrathin junctions have been fabricated with distinct processes for the p-region creation: either with Aluminium conventional ion implantation, or with Boron Plasma Ion Immersion Implantation.
Abstract: 4H-SiC p+n photodiodes based on ultrathin-junctions have been fabricated with distinct processes for the p+-region creation: either with Aluminium conventional ion implantation, or with Boron Plasma Ion Immersion Implantation. Spectral sensitivity measurements were performed at several temperatures from room temperature up to 340°C, with incident wavelengths ranging from 200 to 400 nm. Both responses are characterized by a stability between 200 and 270 nm, and a important increase with temperature between 270 and 380 nm. This fact has to be related to the two different kinds of optical absorption phenomena in SiC with respect to the wavelength, which are direct and indirect (phonon assisted) transitions. When decreasing the temperature, we noticed a hysteresis effect, which could be due to charge trapping by temperature activated defects. After strong proton and electron irradiations, the diodes showed a stability of the response below 270 nm, making them suitable for use in harsh environments. Simulation was performed at room temperature, with a good correlation between simulated and experimental room temperature curves.
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TL;DR: In this article, the spectral sensitivity measurements versus temperature have been carried out on irradiated SiC p+n photodiodes, fabricated using two different doping processes: Aluminium standard implantation and Boron plasma immersion ion implantation.
Abstract: Spectral sensitivity measurements versus temperature have been carried out on irradiated SiC p+n photodiodes, fabricated using two different doping processes: Aluminium standard implantation and Boron plasma immersion ion implantation. The spectral sensitivity of Al doped photodiodes increase for incident wavelength higher than 270 nm, and are very stable below. Boron doped irradiated photodiodes show a general increase of the photoresponse for all wavelengths. In both cases, an hysteresis effect is observable when with the temperature. Results are presented and discussed.
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Abstract: 4H-SiC ultraviolet photodetectors based on Schottky barriers have been formed on lightly doped n-type epitaxial layers grown by chemical vapor deposition method on industrial substrates. The diode structures were irradiated at 25°C with 167 MeV Xe ions at a fluence of 6x109 cm-2. Comparative studies of the optical and electrical properties of initial and irradiated structures with Schottky barriers were carried out in temperature range 23-180°C. Swift heavy ion stimulated changes in photosensitivity and electrical characteristics of the initial and irradiated detectors are explained in terms of the fluctuation traps model with the subsequent thermal dissociation.
1 citations
Cites background from "4H-SiC P+N UV Photodiodes: Influenc..."
...The behavior of the long wavelength edge of photosensitivity (λ ≥ 250 nm) with temperature can be attributed to indirect and direct optical transitions and to changes in the bandgap width [2,3]....
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01 Jan 1989
TL;DR: In this article, a handbook to predict the degradation of solar cell electrical performance in any given space radiation environment is presented, where the interaction of energetic charged particles radiation with solar cells is discussed and the concept of 1 MeV equivalent electron fluence is introduced.
Abstract: The handbook to predict the degradation of solar cell electrical performance in any given space radiation environment is presented. Solar cell theory, cell manufacturing and how they are modeled mathematically are described. The interaction of energetic charged particles radiation with solar cells is discussed and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence are presented.
230 citations
TL;DR: In this article, a high performance 4H-SiC p-i-n photodetector for visible-blind ultraviolet (UV) applications has been designed and fabricated.
Abstract: A high-performance 4H-SiC p-i-n photodetector for visible-blind ultraviolet (UV) applications has been designed and fabricated. The electrical and optical characteristics were measured at room temperature. The photodetector suffered from significant dark current of 2.5 pA/mm2 at reverse bias of 5 V, and the UV light photocurrent was larger than four orders of magnitude higher than the dark current. The built-in potential and the unintentional i-layer doping concentration were obtained from capacitance-voltage (C-V) measurements. The spectral peak responsivity of the detector reached 0.13 A/W at a wavelength of 270 nm, corresponding to a maximum external quantum efficiency of ∼61%. And the ratio of responsivity at 270 nm to that at 380 nm was >103. The characteristics imply that the photodetector has a great improved ultraviolet-visible rejection ratio which is needed for ultraviolet signal detection.
183 citations
TL;DR: In this article, a deep Ultraviolet (UV) photodiode was fabricated using a heterojunction between β-Ga2O3 and 6H-SiC with a band gap of 3.02
Abstract: A deep Ultraviolet (UV) photodiode was fabricated using a heterojunction between β-Ga2O3 with a band gap of 4.9 eV, and 6H-SiC with a band gap of 3.02 eV, and investigated its UV sensitivity. A thin β-Ga2O3 layer (200 nm) was prepared on a p-type 6H-SiC substrate through gallium evaporation in oxygen plasma. The device showed good rectifying properties. Under reverse bias, the current increased linearly with increasing deep-UV light intensity. The responsivity of the photodiode was highest to deep-UV light below a wavelength of 260 nm. The photodiode's response time to deep-UV light was in the order of milliseconds.
178 citations
TL;DR: In this article, a correlation study between lifetime and various deep levels was conducted to identify the Z1/2 and/or EH6/7 centers as effective recombination centers.
Abstract: Carrier lifetimes in n-type 4H-SiC epilayers have been investigated by differential microwave photoconductance decay measurements. Through a correlation study between lifetime and various deep levels, the Z1/2 and/or EH6/7 centers have been identified as effective recombination centers. When the Z1/2 (and EH6/7) concentration is higher than 1013 cm–3, the inverse carrier lifetime is in proportion to the trap concentration, and the lifetime increases with increasing excitation intensity (density of irradiated photons). Alternartively, other recombination processes limit the lifetime when the Z1/2 concentration is less than 1013 cm–3. In this case, the carrier lifetime is decreased by increasing the excitation intensity. Surface recombination and recombination in the substrate have been suggested based on numerical analyses as the other recombination paths. By controlling the Z1/2 (and EH6/7) concentration by low-energy electron irradiation, lifetime control has been achieved. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
123 citations
TL;DR: In this paper, the dielectric functions of bulk 4H and 6H SiC from 072 to 66 eV for light propagating nearly parallel to the hexagonal axis were measured using rotating-analyzer ellipsometry employing a compensator and optical transmission.
Abstract: Spectroscopic rotating-analyzer ellipsometry employing a compensator and optical transmission were used to measure the dielectric functions of bulk 4H and 6H SiC from 072 to 66 eV for light propagating nearly parallel to the hexagonal axis The measurements below the band gap show the presence of a thin surface layer, which was modeled as SiO2 The data are similar to results for cubic (3C) and 6H SiC from the literature, but differences are notable, particularly above 4 eV At 556 eV, we observe a critical point in 4H SiC, which is assigned to direct interband transitions along the U=M−L axis in the hexagonal Brillouin zone after comparison with band structure calculations No evidence for direct transitions below 65 eV was found in 6H SiC We apply our results to the analysis of a 4H SiC film on insulator (SiCOI) produced by high-dose hydrogen implantation and direct wafer bonding on Si For comparison, we also studied a 1 μm thick epitaxial layer of 3C SiC on Si, where the interference oscillations
85 citations