Ge-on-GaAs film resistance thermometers: Low-temperature conduction and magnetoresistance

Mitin, V. F.; Kholevchuk, V. V.; Kolodych, B.P.

doi:10.1016/j.cryogenics.2010.11.003

Cited by 25 publications

(13 citation statements)

References 31 publications

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“…Considering several material choices and strain engineering in the channel, Ge epitaxial film grown on a large bandgap GaAs material is of immense interest due to lattice match (mismatch $0.07%) which ensures larger critical thickness, lower dislocation density, and strain-free Ge epitaxial film. As a result, highhole mobility of Ge and its narrow bandgap (E g ¼ 0.67 eV) make the GaAs/Ge heterojunction suitable for the fabrication of p-channel QW field effect transistors, 17 solar cells, 18 metal-oxide semiconductor field effect transistors, 19,20 millimeter-wave mixer diodes, 21 temperature sensors, 22 photodetectors, 23,24 and quantum confinement devices. 25 In order to realize a high-performance Ge QW transistor structure, higher bandgap III-V barrier layers are essential in order (i) to eliminate parallel conduction, 2,3 (ii) to provide large valence band offset (DE v !…”

Section: Introductionmentioning

confidence: 99%

In situ grown Ge in an arsenic-free environment for GaAs/Ge/GaAs heterostructures on off-oriented (100) GaAs substrates using molecular beam epitaxy

Hudait

Zhu

Jain

et al. 2012

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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High-quality epitaxial Ge layers for GaAs/Ge/GaAs heterostructures were grown in situ in an arsenic-free environment on (100) off-oriented GaAs substrates using two separate molecular beam epitaxy (MBE) chambers, connected via vacuum transfer chamber. The structural, morphological, and band offset properties of these heterostructures are investigated. Reflection high energy electron diffraction studies exhibited (2 Â 2) Ge surface reconstruction after the growth at 450 C and also revealed a smooth surface for the growth of GaAs on Ge. High-resolution triple crystal x-ray rocking curve demonstrated high-quality Ge epilayer as well as GaAs/Ge/(001)GaAs heterostructures by observing Pendell€ osung oscillations and that the Ge epilayer is pseudomorphic. Atomic force microscopy reveals smooth and uniform morphology with surface roughness of $0.45 nm and room temperature photoluminescence spectroscopy exhibited direct bandgap emission at 1583 nm. Dynamic secondary ion mass spectrometry depth profiles of Ga, As, and Ge display a low value of Ga, As, and Ge intermixing at the Ge/GaAs interface and a transition between Ge/GaAs of less than 15 nm. The valence band offset at the upper GaAs/Ge-(2 Â 2) and bottom Ge/(001)GaAs-(2 Â 4) heterointerface of GaAs/Ge/GaAs double heterostructure is about 0.20 eV and 0.40 eV, respectively. Thus, the high-quality heterointerface and band offset for carrier confinement in MBE grown GaAs/Ge/GaAs heterostructures offer a promising candidate for Ge-based p-channel high-hole mobility quantum well field effect transistors. V

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Section: Introductionmentioning

confidence: 99%

In situ grown Ge in an arsenic-free environment for GaAs/Ge/GaAs heterostructures on off-oriented (100) GaAs substrates using molecular beam epitaxy

Hudait

Zhu

Jain

et al. 2012

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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“…It shows a considerable advantage over other TI systems including graphene [3], HgTe QW, [4,5] the Bi chalcogenides [9] and the Heusler compounds [12,17]. GaAs/Ge/GaAs sandwiched structures are readily to be integrated with conventional semiconductors which are already extensively used in electronic devices [23][24][25][26][27][28][29][30][31]. The imposed electric field can be controlled by applying extra electric field or by inducing holes or electrons into the QW region via a gate voltage, providing us a direct way of manipulating the TI transition in the device.…”

mentioning

confidence: 99%

“…[23][24][25][26] Ge/GaAs interfaces with exceedingly small lattice mismatch posses many advantages over the strained interface. Ge layers grown on GaAs substrate were studied because of their widespread applications in solar cells, [27] metal-oxide-semiconductor field-effect transistors, [28] millimeter-wave mixer diodes, [29] temperature sensors, [30] and photodetectors. [31] Considering a GaAs/Ge/GaAs quantum well (QW) grown along the polar direction [111] (see Fig.…”

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confidence: 99%

Interface-Induced Topological Insulator Transition inGaAs/Ge/GaAsQuantum Wells

Zhang¹,

Lou²,

Miao³

et al. 2013

Phys. Rev. Lett.

138

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We demonstrate theoretically that interface engineering can drive Germanium, one of the most commonly-used semiconductors, into topological insulating phase. Utilizing giant electric fields generated by charge accumulation at GaAs/Ge/GaAs opposite semiconductor interfaces and band folding, the new design can reduce the sizable gap in Ge and induce large spin-orbit interaction, which lead to a topological insulator transition. Our work provides a new method on realizing TI in commonly-used semiconductors and suggests a promising approach to integrate it in well developed semiconductor electronic devices.PACS numbers: 71.70. Ej, 75.76.+j, 72.25.Mk Time-reversal invariant topological insulators (TIs) have aroused intensive interests in the past years, with tantalizing properties such as insulating bulk, robust metallic edge or surface modes and exotic topological excitations, and potential applications ranging from spintronics to quantum computation. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Despite these successful progresses, the topological insulator materials are still limited in the narrow gap materials containing heavy atoms, e.g., HgTe, [4,5] Bi 2 X 3 (X=Se, Te,...) [8][9][10][11], transition metal oxide heterostructure [16] and Heusler compounds [12,17]. These materials are often very different from conventional semiconductor materials in structures and properties and are hard to be integrated in current electronics devices that are based on well developed semiconductor fabrication technologies.Although there are theoretical predicts about realizing TI states in graphene, [3,18,19] the main obstacle is the weak intrinsic spin-orbit interaction (SOI) of carbon atoms. Here, instead of searching new TI materials with exotic structures and chemical elements, we take a totally different route: driving the commonly used semiconductors into TI states by using the intrinsic electric field and the strains. The difficulty of this approach lies in the fact that most of the commonly used semiconductors, such as Si, Ge, GaAs and many others usually possess sizable band gaps and do not have strong enough SOI. Furthermore, group IV elements such as Si and Ge have indirect band gap, posing extra difficulty in realizing TI. Inspired by recent theoretical works that the normal insulator [20] can be driven into a TI by an external electric field, our approach is to impose huge electric field by deliberately designed heterostructures. Recently, an interesting way of realizing topological insulating phase in a p-type GaAs quantum well by two-dimentional superimposed potentials with hexagonal symmetry was proposed.[21] Different to that work, our approach rely completely on the material engineering at the atomic level.Since commonly-used semiconductors, e.g., Si, Ge, GaAs, posses sizable bandgap ranging from 0.8eV to 1.4eV, a huge electric field is required to closing bandgap and even invert the conduction and valence bands. Such huge electric field can not be generated utilizing the gate technique. However, recent ...

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“…The study of Ge/GaAs heterostructures is of great interest due to their widespread applications in solar cells, 1-4 metaloxide-semiconductor field-effect transistors, 5 millimeter-wave mixer diodes, 6 temperature sensors, [7][8][9] and photodetectors. 7,10 Because of the small lattice mismatch, and the similar thermal expansion coefficients of Ge and GaAs, 1 Ge/GaAs heterojunctions are favorable for epitaxial growth and an excellent model system for IV/III-V heterostructure in general.…”

Section: Introductionmentioning

confidence: 99%

Tailoring the electrical properties of Ge/GaAs by film deposition rate and preparation of fully compensated Ge films

et al. 2011

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We investigate the electronic, optical, and structural properties of thin Ge/GaAs(100) films for a variety of growth rates. All of the films have a granular, single-crystal structure, but the electronic properties vary dramatically, with resistivity and carrier concentration changing by more than three orders of magnitude. For high deposition rates, the films are heavily doped and of n-type, with relatively high carrier concentration and low resistivity. The temperature dependence of the resistivity indicates metalliclike transport with degenerate charge carriers. For low deposition rates, the films are p-type, with lower carrier concentrations and higher resistivity whose temperature dependence indicates semiconducting, activation-type transport with an activation energy that can reach up to half of the Ge band gap. Such films are heavily doped and strongly (sometimes fully) compensated Ge. At moderate deposition rates, a metal-insulator transition occurs. The electrical properties of strongly compensated Ge films are analyzed in terms of the two-dimensional percolation of charge carriers through a fluctuating electrostatic potential.

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Ge-on-GaAs film resistance thermometers: Low-temperature conduction and magnetoresistance

Cited by 25 publications

References 31 publications

In situ grown Ge in an arsenic-free environment for GaAs/Ge/GaAs heterostructures on off-oriented (100) GaAs substrates using molecular beam epitaxy

In situ grown Ge in an arsenic-free environment for GaAs/Ge/GaAs heterostructures on off-oriented (100) GaAs substrates using molecular beam epitaxy

Interface-Induced Topological Insulator Transition inGaAs/Ge/GaAsQuantum Wells

Tailoring the electrical properties of Ge/GaAs by film deposition rate and preparation of fully compensated Ge films

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