Depletion region

About: Depletion region is a research topic. Over the lifetime, 9393 publications have been published within this topic receiving 145633 citations.

Temperature-independent field-induced charge separation at doped organic/organic interfaces: Experimental modeling of electrical properties

Abstract: We examine field-induced charge-carrier separation at doped organic/organic heterointerfaces consisting of tetrafluorotetracyanoquinodimethane doped $4,{4}^{\ensuremath{'}},{4}^{\ensuremath{''}}$-tris($N$-1-naphtyl-$N$-phenylamino)-triphenylamine as hole-transporting layer and Li-doped 1,3,5-tri(phenyl-2-benzimidazole)-benzene as electron-transporting layer. Low-temperature $I\text{\ensuremath{-}}V$ characteristics, thickness-dependent $I\text{\ensuremath{-}}V$ characteristics, and Kelvin probe measurements are used to model the energy-level alignment at the interface. No explicit temperature dependence is observed. Thickness-dependent $I\text{\ensuremath{-}}V$ characteristics and Kelvin probe measurements give evidence for a $5\text{\ensuremath{-}}\mathrm{nm}$-thin depletion layer adjacent to the interface. Consistent with our experimental results, we propose a model of electrons tunneling through the depletion zone from the highest occupied molecular orbit of the hole-transporting material to the lowest unoccupied molecular orbit of the electron-transporting material. This generates an electron-hole pair, which dissociates under the intense electric field close to the interface.

The Transitional Heterojunction Behavior of PbS/ZnO Colloidal Quantum Dot Solar Cells

Abstract: The nature of charge separation at the heterojunction interface of solution processed lead sulphide-zinc oxide colloidal quantum dot solar cells is investigated using impedance spectroscopy and external quantum efficiency measurements to examine the effect of varying the zinc oxide doping density. Without doping, the device behaves excitonically with no depletion region in the PbS layer such that only charge carriers generated within a diffusion length of the PbS/ZnO interface have a good probability of being harvested. After the ZnO is photodoped such that the doping density is near or greater than that of the PbS, a significant portion of the depletion region is found to lie within the PbS layer increasing charge extraction (p–n operation).

Modelling the electric potential distribution in the dark in nanoporous semiconductor electrodes

Abstract: This study concerns the electric potential distribution in the dark in nanocrystalline porous semiconductor electrodes, in full depletion conditions. Since band bending in a single colloidal particle is small, the idea is to develop a model that accounts for the total potential drop resulting from the equilibration between the Fermi level and the redox potential in the solution. As preliminary steps, the band bending and potential distribution in a planar electrode and also in a colloidal semiconductor particle are reviewed. In order to overcome the limitations of results based on these geometries, a model based on a columnar shape is developed. The Poisson equation is solved in the columnar electrode, with careful consideration of the boundary conditions. A large potential drop is shown to take place at the back contact. To complete the study, the effect of the depletion zone in the transparent conducting oxide is analysed. Simple expressions are derived that permit evaluation of how the total potential drop is distributed between the electrode and the substrate. From this, the strength and spatial range of the electric field in the electrode can be estimated.

Current-voltage and capacitance-voltage characteristics of Sn/rhodamine-101∕n-Si and Sn/rhodamine-101∕p-Si Schottky barrier diodes

Abstract: The nonpolymeric organic compound rhodamine-101 (Rh101) film on a n-type Si or p-type Si substrate has been formed by means of the evaporation process and the Sn/rhodamine-101/Si contacts have been fabricated. The Sn∕Rh101∕n-Si and Sn∕Rh101∕p-Si contacts have rectifying contact behavior with the barrier height (BH) values of 0.714 and 0.827eV, and with ideality factor values of 2.720 and 2.783 obtained from their forward bias current-voltage (I-V) characteristics at room temperature, respectively. It has been seen that the BH value of 0.827eV obtained for the Sn∕Rh101∕p-Si contact is significantly larger than BH values of the conventional Sn∕p-Si Schottky diodes and metal/interfacial layer/Si contacts. Thus, modification of the interfacial potential barrier for metal/Si diodes has been achieved using a thin interlayer of the Rh101 organic semiconductor; this has been ascribed to the fact that the Rh101 interlayer increases the effective barrier height by influencing the space charge region of Si.

Field effect transistor and manufacturing method thereof

Abstract: A field effect transistor includes a first semiconductor region forming a channel region, a gate electrode insulatively disposed above the first semiconductor region, source and drain electrodes formed to sandwich the first semiconductor region in a channel lengthwise direction, and second semiconductor regions formed between the first semiconductor region and the source and drain electrodes and having impurity concentration higher than the first semiconductor region. The thickness of the second semiconductor region in the channel lengthwise direction is set to a value equal to or less than depletion layer width determined by the impurity concentration so that the second semiconductor region is depleted in a no-voltage application state.