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Depletion region

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


Papers
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Journal ArticleDOI
TL;DR: The combined effects of a significant back-contact barrier and a low absorber carrier density frequently alter the currentvoltage (J-V) characteristics of CdTe solar cells.
Abstract: The combined effects of a significant back-contact barrier and a low absorber carrier density frequently alter the current-voltage (J-V) characteristics of CdTe solar cells. This combination leads to two competing mechanisms that can alter the J-V characteristics in two different ways. One is a majority-carrier (hole) limitation on current in forward bias that reduces the fill factor and efficiency of the solar cell. The second is a high minority-carrier (electron) contribution to the forward diode current that results in a reduced open-circuit voltage. CdTe solar cells are particularly prone to the latter, since the combination of a wide depletion region and impedance of light-generated holes at the back contact increases the electron injection at the front diode. The overlap of front and back space-charge regions will generally enhance the electron current, but is not a requirement for substantially increased forward current. The simulated J-V curves, illustrating the two major effects, are in good agre...

48 citations

Proceedings ArticleDOI
23 Jan 2010
TL;DR: In this article, a mid-wave infrared photodetectors containing InAsSb absorber regions and AlAsB barriers in n-barrier-n (nBn) and n-barrrier-p(nBp) configurations were fabricated and characterized by currentvoltage, photocurrent, and capacitance-voltage measurements in the 100-200 K temperature range.
Abstract: We have fabricated mid-wave infrared photodetectors containing InAsSb absorber regions and AlAsSb barriers in n-barrier-n (nBn) and n-barrier-p (nBp) configurations, and characterized them by current-voltage, photocurrent, and capacitance-voltage measurements in the 100-200 K temperature range. Efficient collection of photocurrent in the nBn structure requires application of a small reverse bias resulting in a minimum dark current, while the nBp devices have high responsivity at zero bias. When biasing both types of devices for equal dark currents, the nBn structure exhibits a differential resistance significantly higher than the nBp, although the nBp device may be biased for arbitrarily low dark current at the expense of much lower dynamic resistance. Capacitance-voltage measurements allow determination of the electron concentration in the unintentionally-doped absorber material, and demonstrate the existence of an electron accumulation layer at the absorber/barrier interface in the nBn device. Numerical simulations of idealized nBn devices demonstrate that photocurrent collection is possible under conditions of minimal absorber region depletion, thereby strongly suppressing depletion region Shockley-Read-Hall generation.

48 citations

Journal ArticleDOI
TL;DR: These studies reveal that, in addition to modulation of the depletion region in n-SrTiO_{3}, the BaTiO_3} barrier layer becomes conducting near the interface for polarization pointing into n- SrTi O_{3], leading to dramatic enhancement of TER.
Abstract: Realizing a large tunneling electroresistance (TER) effect is crucial for device application of ferroelectric tunnel junctions (FTJs) FTJs are typically composed of a thin ferroelectric layer sandwiched by two metallic electrodes, where TER generally results from the dependence of the effective tunneling barrier height on the ferroelectric polarization Since the resistance depends exponentially not only on barrier height but also on barrier width, TER is expected to be greatly enhanced when one of the electrodes is a semiconductor where the depletion region near the interface can be controlled via ferroelectric polarization To explore this possibility, we perform studies of SrRuO_{3}/BaTiO_{3}/n-SrTiO_{3} FTJs, where n-SrTiO_{3} is an electron doped SrTiO_{3} electrode, using first-principles density functional theory Our studies reveal that, in addition to modulation of the depletion region in n-SrTiO_{3}, the BaTiO_{3} barrier layer becomes conducting near the interface for polarization pointing into n-SrTiO_{3}, leading to dramatic enhancement of TER The effect is controlled by the band alignment between the semiconductor and the ferroelectric insulator and opens the way for experimental realization of enhanced TER in FTJs through the choice of a semiconducting electrode and interface engineering

48 citations

Journal ArticleDOI
TL;DR: In this article, the relationship between electronic structure, optical properties, and PEC activity of Sn-doped Fe2O3 was determined by studying highly crystalline, well-controlled thin films prepared by pulsed laser deposition (PLD).
Abstract: Hematite (Fe2O3) is a well-known oxide semiconductor suitable for photoelectrochemical (PEC) water splitting and industry gas sensing. It is widely known that Sn doping of Fe2O3 can enhance the device performance, yet the underlying mechanism remains elusive. In this work, we determine the relationship between electronic structure, optical properties, and PEC activity of Sn-doped Fe2O3 by studying highly crystalline, well-controlled thin films prepared by pulsed laser deposition (PLD). We show that Sn doping substantially increases the n-type conductivity of Fe2O3, and the conduction mechanism is better described by a small-polaron hopping (SPH) model. Only 0.2% Sn doping significantly reduces the activation energy barrier for SPH conduction from at least 0.5 eV for undoped Fe2O3 to 0.14 eV for doped ones. A combination of X-ray photoemission, X-ray absorption spectroscopy, and DFT calculations reveals that the Fermi level gradually shifts toward the conduction band minimum with Sn doping. A localized Fe2+-like gap state is observed at the top of the valence band, accounting for the SPH conduction. Interestingly, different from the literature, only 0.2% Sn doping in Fe2O3 significantly improves the PEC activity, while more Sn decreases it. The improved PEC activity is partially attributed to an increased band bending potential which facilitates the charge separation at the space charge region. The reduced activation energy barrier for SPH will facilitate the transport of photoexcited carriers for the enhanced PEC, which is of interest for further carrier dynamics study.

48 citations

Patent
11 Sep 2008
TL;DR: In this paper, a bipolar type semiconductor device capable of attaining high current gain and high cut-off frequency and performing a satisfactory transistor operation also in a high current region while maintaining a high breakdown voltage performance, as well as a method of manufacturing the semiconductor devices, are provided.
Abstract: A bipolar type semiconductor device capable of attaining high current gain and high cut-off frequency and performing a satisfactory transistor operation also in a high current region while maintaining a high breakdown voltage performance, as well as a method of manufacturing the semiconductor device, are provided. In a collector comprising a first semiconductor layer and a second semiconductor layer narrower in band gap than the first semiconductor layer, an impurity is doped so as to have a peak of impurity concentration within the second collector layer and so that the value of the peak is higher than the impurity concentration at any position within the first collector layer. It is preferable to adjust the concentration of the doped impurity in such a manner that a collector-base depletion layer extends up to the first collector layer.

48 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202326
202266
2021151
2020198
2019229
2018239