Modeling of tunneling current density of GeC based double barrier multiple quantum well resonant tunneling diode
TL;DR: In this paper, the double barrier quantum well (DBQW) resonant tunneling diode (RTD) structure made of SiGeSn/GeC/SiGeSn alloys grown on Ge substrate is analyzed.
Abstract: The double barrier quantum well (DBQW) resonant tunneling diode (RTD) structure made of SiGeSn/GeC/SiGeSn alloys grown on Ge substrate is analyzed. The tensile strained Ge1−zCz on Si1−x−yGexSny heterostructure provides a direct band gap type I configuration. The transmission coefficient and tunneling current density have been calculated considering single and multiple quantum wells. A comparative study of tunnelling current of the proposed structure is done with the existing RTD structure based on GeSn/SiGeSn DBH. A higher value of the current density for the proposed structure has been obtained.
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TL;DR: In this article, a tensile-strained type I direct band gap QWIP (QWIP) structure is proposed, where the active region has a multiple quantum well structure formed with Ge0.92Sn0.08 quantum wells separated by Si0.11Ge0.7Sn 0.19 barriers.
Abstract: QWIP using group IV elements have created more interest among researchers for its potential application in optical communication as well as in optical interconnects. This paper presents modeling and theoretical analysis of Sn-based tensile strained type I direct band gap QWIP in which the active region has a multiple quantum well structure formed with Ge0.92Sn0.08 quantum wells separated by Si0.11Ge0.7Sn0.19 barriers. The structure reported by V. Ryzhii et al. has been reproduced and the parameters like responsivity, power density and the dark current density have been analytically calculated. A comprehensive comparison of responsivity and power density of this proposed structure with the existing QWIP structure made of GaAs/InGaAs is reported here. An improvement in the field of responsivity is observed with the proposed model. The reduction of threshold power density corresponds to an effective operation of the QWIPs in incident infrared radiation. The intersubband electron transition and tunneling electron injection effects are considered here to predict a better performance of the proposed structure operated in infrared region.
1 citations
Dissertation•
12 Apr 2019
TL;DR: In this paper, the authors investigated the functionality of three different types of tunnel diodes, namely, Single Barrier Asymmetric Spacer Tunnel (ASPAT), Double Quantum Well Asynchronic Spacer Tunnelling Diode, and a Double Barrier Quantum Well Resonant Tunneling Diode (RTD), with the aim to investigate the capabilities of each tunnel device.
Abstract: It has been over a half-century since Leo Esaki in the early 1960 reported the first tunnel diodes. These first quantum electron tunnelling devices were named Esaki diode in his honour. This was a testament to quantum transport in a semiconductor which was subsequently demonstrated to be extremely stable. The work reported in this thesis probed into the functionality of three new and different types of tunnel diodes, namely a Single Barrier Asymmetric Spacer Tunnel (ASPAT), a Double Quantum Well Asymmetric Spacer Tunnel (QASPAT), and a Double Barrier Quantum Well Resonant Tunnelling Diode (RTD), with the aim to investigate the capabilities of each tunnel device.
Adorned with the status of a maturing tunnel diode within the semiconductor arena, the ASPAT diode appears to be an exceptionally promising candidate for high-frequency applications, due to its highest theoretical cut-off frequency which can reach up to 2 THz. Its asymmetric spacer structure leads to a unique asymmetrical I-V characteristic that offers significant improvement over Schottky and Planar Doped Barrier (PDB) diodes without sacrificing sensitivity or dynamic range aspects. Such stimulating feature is indeed paramount for implementations of high-speed detectors, especially for operations in the mm-wave/THz regime.
In this research, an original and novel idea to tweak the ASPAT structure has led to a most remarkable feature that reflects a dual-function device in a single diode. Originating from the ASPAT structure, the I-V characteristic has zero-bias turn-on feature but showed a most interesting feature of negative differential resistance (NDR) region in reverse bias enabling this device to function as both a detector and an oscillator, depending on bias voltage. This device is temperature independent as its I-V characteristics does exhibit insensitivity to temperature over a wide range of temperature variations. It displays less than ~ 5 % current change when compared to the I-V characteristics at selected temperatures (from 77 K to 400 K), to the I-V at room temperature.
Quantum based devices, particularly RTD, appears to be promising devices that possess the capability of providing close to ~ 1 mW of RF power in the millimetre wave and THz regions of the electromagnetic spectrum. This feature is mainly attributed to their unique NDR feature showcased in the I-V characteristic of the RTDs reported here. Following modelling and validation of ASPAT and QASPAT diodes with high indium-rich material profiles, the study was then extended to quantum modelling of advanced double barrier In0.8Ga0.2As/AlAs RTD.
The work culminated in an accurate physical model which was exploited to minimise fabrication costs in developing experimental devices. The two-dimensional (2D) simulation for all devices under study demonstrated outstanding agreement with the measured DC and RF characteristics validating the models used.
19 Dec 2019
TL;DR: In this paper, the high-frequency performance of GeSn-SiGeSn QWIP has been studied considering the intersubband transition and transit time effect of electrons, and the band structure and the analytical results of responsivity are also presented.
Abstract: QWIP using group IV elements are of great research attention for its potential application in optical communication and in optical interconnects. The high-frequency performance of GeSn–SiGeSn QWIP has been studied considering the intersubband transition and transit time effect of electrons. The band structure of GeSn–SiGeSn QWIP and the analytical results of responsivity are also presented in this paper.
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IBM1
TL;DR: The study of superlattices and observations of quantum mechanical effects on a new physical scale may provide a valuable area of investigation in the fieId of semiconductors.
Abstract: We consider a one-dimensional periodic potential, or "superlattice," in monocrystalline semiconductors formbeyd a periodic variation of alloy composition or of impurity density introduced during epitaxial growth. If the period of a superlattice, of the order of 100A, is shorter than the electron mean free path, a series of narrow allowed and forbidden bands is expected duet o the subdivision of the Brillouin zone into a series of minizones. If the scattering time of electrons meets a threshold condition, the combined effect of the narrow energy band and the narrow wave-vector zone makes it possible for electrons to be excited with moderate electric fields to an energy and momentum beyond an inflection point in the E-k relation; this results ina negative differential conductance in the direction of the superlattice. The study of superlattices and observations of quantum mechanical effects on a new physical scale may provide a valuable area of investigation in the fieId of semiconductors.
2,569 citations
TL;DR: In this article, the transport properties of a finite superlattice from the tunneling point of view have been computed for the case of a limited number of spatial periods or a relatively short electron mean free path.
Abstract: We have computed the transport properties of a finite superlattice from the tunneling point of view. The computed I‐V characteristic describes the experimental cases of a limited number of spatial periods or a relatively short electron mean free path.
1,996 citations
TL;DR: In this article, a double-barrier structure with a thin GaAs sandwiched between two GaAlas barriers has been shown to have resonance in the tunneling current at voltages near the quasistationary states of the potential well.
Abstract: Resonant tunneling of electrons has been observed in double‐barrier structures having a thin GaAs sandwiched between two GaAlas barriers. The resonance manifests itself as peaks or humps in the tunneling current at voltages near the quasistationary states of the potential well. The structures have been fabricated by molecular beam epitaxy which produces extremely smooth films and interfaces.
1,633 citations
Journal Article•
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TL;DR: In this paper, the authors provide an overview of the state of the art in silicon photonics and outline challenges that must be overcome before large-scale commercialization can occur, in particular, for realization of integration with CMOS very large scale integration (VLSI) and must operate within thermal constraints of VLSI chips.
Abstract: After dominating the electronics industry for decades, silicon is on the verge of becoming the material of choice for the photonics industry: the traditional stronghold of III-V semiconductors. Stimulated by a series of recent breakthroughs and propelled by increasing investments by governments and the private sector, silicon photonics is now the most active discipline within the field of integrated optics. This paper provides an overview of the state of the art in silicon photonics and outlines challenges that must be overcome before large-scale commercialization can occur. In particular, for realization of integration with CMOS very large scale integration (VLSI), silicon photonics must be compatible with the economics of silicon manufacturing and must operate within thermal constraints of VLSI chips. The impact of silicon photonics will reach beyond optical communication-its traditionally anticipated application. Silicon has excellent linear and nonlinear optical properties in the midwave infrared (IR) spectrum. These properties, along with silicon's excellent thermal conductivity and optical damage threshold, open up the possibility for a new class of mid-IR photonic devices
701 citations
TL;DR: In this paper, a class of Si-based semiconductors in the Ge1−xSnx system is described, which is completely characterized by Rutherford backscattering, low-energy secondary ion mass spectrometry, high-resolution transmission electron microscopy, x-ray diffraction (rocking curves), as well as infrared and Raman spectroscopies and spectroscopic ellipsometry.
Abstract: We describe a class of Si-based semiconductors in the Ge1−xSnx system. Deuterium-stabilized Sn hydrides provide a low-temperature route to a broad range of highly metastable compositions and structures. Perfectly epitaxial diamond-cubic Ge1−xSnx alloys are grown directly on Si(100) and exhibit high thermal stability, superior crystallinity, and crystallographic and optical properties, such as adjustable band gaps and lattice constants. These properties are completely characterized by Rutherford backscattering, low-energy secondary ion mass spectrometry, high-resolution transmission electron microscopy, x-ray diffraction (rocking curves), as well as infrared and Raman spectroscopies and spectroscopic ellipsometry. Ab initio density functional theory simulations are also used to elucidate the structural and spectroscopic behavior.
241 citations