Depletion region

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

Consecutive Junction-Induced Efficient Charge Separation Mechanisms for High-Performance MoS2/Quantum Dot Phototransistors

Abstract: Phototransistors that are based on a hybrid vertical heterojunction structure of two-dimensional (2D)/quantum dots (QDs) have recently attracted attention as a promising device architecture for enhancing the quantum efficiency of photodetectors. However, to optimize the device structure to allow for more efficient charge separation and transfer to the electrodes, a better understanding of the photophysical mechanisms that take place in these architectures is required. Here, we employ a novel concept involving the modulation of the built-in potential within the QD layers for creating a new hybrid MoS2/PbS QDs phototransistor with consecutive type II junctions. The effects of the built-in potential across the depletion region near the type II junction interface in the QD layers are found to improve the photoresponse as well as decrease the response times to 950 μs, which is the faster response time (by orders of magnitude) than that recorded for previously reported 2D/QD phototransistors. Also, by implement...

Proposed design of a Josephson diode.

Abstract: We propose a new type of Josephson junction formed by two superconductors close to the superconductor-Mott-insulator transition, one of which is doped with holes and the other is doped with electrons. A self-organized Mott-insulating depletion region is formed at the interface between two superconductors, giving rise to an asymmetric response of current to the external voltage. The collective excitations of the depletion region result in a novel phase dynamics that can be measured experimentally in the noise spectrum of the Josephson current.

Investigation of Ni/4H-SiC diodes as radiation detectors with low doped n-type 4H-SiC epilayers

Abstract: The development of SiC minimum ionising particle (MIP) detectors imposes severe constrains in the electronic quality and the thickness of the material due to the relatively high value of the energy required to produce an electron–hole pair in this material by MIP against the value for Si. In this work, particle detectors were made using semiconductor epitaxial undoped n-type 4H-SiC as the detection medium. The thickness of the epilayer is on the order of 40 μm and the detectors are realised by the formation of a nickel silicide on the silicon surface of the epitaxial layer (Schottky contact) and of the ohmic contact on the back side of 4H-SiC substrate. The low doping concentration (≅6×10 13 cm −3 ) of the epilayer allows the detector to be totally depleted at relatively low reverse voltages (≅100 V). We present experimental data on the charge collection properties by using 5.486 MeV α-particles impinging on the Schottky contact. A 100% charge collection efficiency (CCE) is demonstrated for reverse voltages higher than the one needed to have a depletion region equal to the α-particle extrapolated range in SiC. The diffusion contribution of the minority change carriers to CCE is pointed out. By comparing measured CCE values to the outcomes of drift–diffusion simulation, values are inferred for the hole lifetime within the neutral region of the charge carrier generation layer.

Frequency response of InP/InGaAsP/InGaAs avalanche photodiodes with separate absorption "grading" and multiplication regions

Abstract: We have measured the frequency response of InP/ InGaAsP/InGaAs photodiodes with separate absorption, "grading," and multiplication regions (SAGM-APD's) for a wide range ( 2 \leq M_{0} \leq 35 ) of dc gains. The results are explained in terms of a theoretical model which incorporates the transit time of carriers through the depletion region, the RC time constant, the accumulation of holes at the valence band discontinuity of the heterojunction interfaces, and the gain-bandwidth limit.

Effect of Quantum Dot Deposition on the Interfacial Flatband Potential, Depletion Layer in TiO2 Nanotube Electrodes, and Resulting H2 Generation Rates

Abstract: CdS QD-modified TiO2 nanotube arrays were fabricated using an anodic oxidation-sequential chemical bath deposition process. By means of FESEM, EDS, XRD and XPS, it could be confirmed that the use of an ultrasonication-assisted deposition approach improved the distribution of CdS QDs on the tube walls. The as-prepared CdS-modified TiO2 nanotube arrays exhibited enhanced photoelectrochemical properties and hydrogen production activity, which benefitted from the extended light absorption and the improved interfacial charge-transfer properties of TiO2 nanotube arrays. By analyzing the interfacial properties, the flatband potential, the depletion layer, the capacitance, and the impedance of the CdS/TiO2 photoelectrode, it can be concluded that compared with pure TiO2 nanotube arrays the CdS QD-modified arrays exhibited a more negative flat band potential and a lower energy barrier for interfacial electron transfer. The calculated depletion layer width (dSC) of the sensitized TiO2 nanotube arrays was larger, wh...