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<i>C–V–f, G–V–f</i> and <i>Z″–Z′</i> Characteristics of <i>n</i> -Type Si/B-Doped <i>p</i> -Type Ultrananocrystalline Diamond Heterojunctions Formed via Pulsed Laser Deposition
摘要： n-Type Si/p-type B-doped ultrananocrystalline diamond heterojunction photodiodes were built using pulsed laser deposition at a heated substrate temperature of 550 °C. Following the capacitance–voltage–frequency (C–V–f) and conductance–voltage–frequency (G–V–f) plots, the series resistance (Rs) values at zero bias voltage were 154.41 Ω at 2 MHz and 1.72 kΩ at 40 kHz. Rs should be ascribed to Rs occurring in the metallic contact and the bulk resistance in the active layer. At 40 kHz, the interface state density (Nss) was 1.78 × 10^13 eV^?1 cm^?2 and dropped exponentially to 1.39 × 10^12 eV^?1 cm^?2 at 2 MHz. An assessed Nss occurring at the heterojunction interface was the cause of deterioration in the photo-detection properties. At different V values, the appearance of the real (Z') and imaginary (Z'') characteristic curves revealed single semicircles whose centers lay below the Z' axis. The magnitude of the curve was diminished with the increment of V. The particularities of Z''–Z' plots can be identified as an equivalent circuit model. The appropriate model included Rs, which was combined with the parallel circuit of resistance and constant phase element.
关键词： UNCD,Interface State Density,Series Resistance,PLD,Impedance
更新于2025-11-14 17:28:48
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Structural Engineering of Dispersed Graphene Flakes into ZnO Nanotubes on Discontinues Ultra‐Nanocrystalline Diamond Substrates for High‐Performance Photodetector with Excellent UV Light to Dark Current Ratios
摘要： In this work, ultraviolet (UV) photodetectors based on ultra-nanocrystalline diamond (UNCD) and dispersed graphene flakes (GrF) with ZnO nanotubes (ZnTs) heterostructures are investigated. Unique hybrid nanostructure of dispersed GrF into ZnTs on discontinuous UNCD substrates using scalable techniques is presented. It is revealed from microstructural analysis that the addition of GrF into highly uniform ZnTs grown on UNCD substrates results outstanding UV photodetection properties. Thus, the GrF-ZnTs/UNCD nanostructure reveals superior UV diode performance, with an ultrahigh UV switching ratio of 19 708 at 5 V, which is excellently better than those of ZnO nanostructures. It is perceived that the perfect distribution of GrF into ZnTs on UNCD substrates results in ultrafast electron–hole recombination. The distribution of GrF and UNCD interlayer enables the new energy levels on the conduction band, which reduces the barrier height to allow fast charge carrier transportation during the UV illumination. It is believed that the addition of GrFs and UNCD layer increase the UV adsorptivity and sufficient amount of conducting path within ZnTs. Therefore, the present GrF-ZnTs/UNCD photodetector can be used as an efficient UV photodetection device with high performance and opening up new opportunities for future optoelectronic devices.
关键词： discontinuous UNCD film,ZnTs-UNCD,ZnTs UV photodetectors,graphene-UNCD,dispersed graphene flakes
更新于2025-09-12 10:27:22
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Diode Parameters of Heterojunctions Comprising <i>p</i> -Type Ultrananocrystalline Diamond Films and <i>n</i> -Type Si Substrates
摘要： In the current research, heterojunctions comprising p-type ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films and n-type Si substrates were formed via pulsed laser deposition. To extract their junction parameters via thermionic emission (TE) theory and Norde model, the measurement of dark current density–voltage curves was carried out under various temperatures ranging from 300 to 60 K. Through TE theory, the ideality factor values at 300 K and 60 K were 2.70 and 8.66, respectively. This justified that a heavy recombination process occurs at the junction interface in addition to another tunneling process at 300 K. The tunneling process is predominant at low temperatures. The barrier height values were 0.78 eV and 0.18 eV at 300 K and 60 K, respectively. The values for series resistance (Rs) at 300 K and 60 K were 275.24 Ω and 78.66 kΩ, respectively. The increment of Rs at low temperatures was likely due to the decrease of carrier concentration in the B-doped UNCD/a-C:H films when temperature was decreased.
关键词： PLD,Thin Films,UNCD/a-C:H,Heterojunction,Junction Parameters
更新于2025-09-09 09:28:46