Coulomb blockade in monolithic and monocrystalline Al-Ge-Al nanowire heterostructures

Sistani, Masiar; Delaforce, Jovian; Bharadwaj, Karthik Srikanth; Luong, Minh Anh; Mendivil, J. Nacenta; Roch, Nicolas; Hertog, M. den; Kramer, R. B. G.; Buisson, Olivier; Lugstein, Alois; Naud, Cécile

doi:10.1063/1.5126088

Cited by 5 publications

(12 citation statements)

References 36 publications

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“…The voltage gap between the diamond peaks is ≈0.88 mV ± 0.02 mV, which corresponds to ∆ = 220 ± 10 μeV which is consistent with the observed gap in QD devices with Al contacts. [ 29,40 ] Further, the measured ∆ agrees with the BCS gap of 222 μeV determined from a critical temperature of T C = 1.46 K. This T C was measured for a pure c‐Al nanowire where all the Ge had diffused out of the nanowire and into the bulk Al pads. [ 41 ] Hereafter, references to the gap are associated with the superconducting gap and not the semiconducting bandgap of Ge.…”

Section: Resultssupporting

confidence: 71%

“…From the odd–even filling effect, affirmed in the Supporting Information, the δ 1 in the many‐hole regime is estimated to be 1.0 ± 0.3 meV. We associate the evolution of E add to the evolution of E C already observed in long Ge segment heterostructures: [ 29 ] as V G decreases the valence band shifts further above the Fermi energy, increasing the size of the QD, thus increasing the magnitude of C S and C D .…”

Section: Resultsmentioning

confidence: 58%

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Al–Ge–Al Nanowire Heterostructure: From Single‐Hole Quantum Dot to Josephson Effect

et al. 2021

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Superconductor–semiconductor–superconductor heterostructures are attractive for both fundamental studies of quantum phenomena in low‐dimensional hybrid systems as well as for future high‐performance low power dissipating nanoelectronic and quantum devices. In this work, ultrascaled monolithic Al–Ge–Al nanowire heterostructures featuring monocrystalline Al leads and abrupt metal–semiconductor interfaces are used to probe the low‐temperature transport in intrinsic Ge (i‐Ge) quantum dots. In particular, demonstrating the ability to tune the Ge quantum dot device from completely insulating, through a single‐hole‐filling quantum dot regime, to a supercurrent regime, resembling a Josephson field effect transistor with a maximum critical current of 10 nA at a temperature of 390 mK. The realization of a Josephson field‐effect transistor with high junction transparency provides a mechanism to study sub‐gap transport mediated by Andreev states. The presented results reveal a promising intrinsic Ge‐based architecture for hybrid superconductor–semiconductor devices for the study of Majorana zero modes and key components of quantum computing such as gatemons or gate tunable superconducting quantum interference devices.

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Section: Resultssupporting

confidence: 71%

Section: Resultsmentioning

confidence: 58%

Al–Ge–Al Nanowire Heterostructure: From Single‐Hole Quantum Dot to Josephson Effect

et al. 2021

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“…Such a system is potentially interesting for SBFET based RFETs with improved on‐currents compared to the Si based systems, as well as for quantum devices that enable the investigation of gate‐tunable charge‐carrier tunneling with both electrons and holes. [ 35,75–77 ] Moreover, in the Si 0.25 Ge 0.75 layer (see Figure 4c) and even more pronounced for the pure Ge layer confined by Si, (see Figure 4d) an increase of resistance of the p‐mode on‐state ( V TG ≤ 0 V) was found, indicating that scattering is the main contribution to the resistance at elevated temperatures. This observation is a further indication for tunneling through a thin barrier, which is determining the transport, rather than thermionic emission.…”

Section: Resultsmentioning

confidence: 92%

Composition Dependent Electrical Transport in Si_1−xGe_xNanosheets with Monolithic Single‐Elementary Al Contacts

Wind

Sistani

Böckle

et al. 2022

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and drain electrodes in highly scaled p-channel field-effect transistors (FETs) for the realization of very-large-scale integration (VLSI) systems. [1] Despite these efforts, the continuous scaling of metaloxide-semiconductor field-effect transistors (MOSFETs) is approaching physical limits where the nature of deterministic charge carrier separation between source and drain by an energy barrier is not applicable anymore. [2,3] In the quest of overcoming scaling limitations, new lines of research arose. Device research has shifted toward new architectures, materials, and technologies to enable "More than Moore" paradigms, [4] extending the mature Si complementary metal-oxidesemiconductor (CMOS) platform. [5] In this regard, Si 1−x Ge x and Ge active regions integrated on Si platforms are promising candidates for future optoelectronic devices [6] and the realization of energy efficient steep subthreshold switches such as band-to-band tunneling transistors (TFETs), [7,8] negative capacitance Ge nanowire FETs, [9,10] and positive feedback FETs. [11] Conventionally, degenerately doped semiconductor regions in combination with thin layers made of transition-metal semiconductor alloys, such as metalsilicides [12] and metal-germanides, [13] have been used to obtain ohmic contacts to most Si 1−x Ge x and Ge based devices. Toward the achievement of ohmic contacts, pinning-free metal semiconductor contacts have been explored in Si and Ge through Si 1−x Ge x is a key material in modern complementary metal-oxide-semiconductor and bipolar devices. However, despite considerable efforts in metal-silicide and -germanide compound material systems, reliability concerns have so far hindered the implementation of metal-Si 1−x Ge x junctions that are vital for diverse emerging "More than Moore" and quantum computing paradigms. In this respect, the systematic structural and electronic properties of Al-Si 1−x Ge x heterostructures, obtained from a thermally induced exchange between ultrathin Si 1−x Ge x nanosheets and Al layers are reported. Remarkably, no intermetallic phases are found after the exchange process. Instead, abrupt, flat, and void-free junctions of high structural quality can be obtained. Interestingly, ultra-thin interfacial Si layers are formed between the metal and Si 1−x Ge x segments, explaining the morphologic stability. Integrated into omega-gated Schottky barrier transistors with the channel length being defined by the selective transformation of Si 1−x Ge x into single-elementary Al leads, a detailed analysis of the transport is conducted. In this respect, a report on a highly versatile platform with Si 1−x Ge x composition-dependent properties ranging from highly transparent contacts to distinct Schottky barriers is provided. Most notably, the presented abrupt, robust, and reliable metal-Si 1−x Ge x junctions can open up new device implementations for different types of emerging nanoelectronic, optoelectronic, and quantum devices.

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“…The important measure of SET behavior is the Coulomb oscillations, a consequence of the periodic modulation of the I ds by V g . − The room temperature Coulomb oscillations are shown in Figure S6 in the absence of bias voltage. The Coulomb peaks corresponding to the addition or subtraction of an electron to or from the Coulomb island are periodic with the average interval Δ V g = 2.5–3 V. The calculated a gate capacitance C g of ∼0.78 aF from Δ V g is in good agreement with the value obtained from the simulation.…”

Section: Resultsmentioning

confidence: 99%

“…The production of germanide contacts by the thermal diffusion of metals into Ge NWs is proficient to improve the contact with Ge structures . However, the resistivity of these quasimetallic systems is considerably greater than that of pure metals. − Therefore, suitable material combinations excluding intermetallic phase formation realizes the metal–semiconductor heterostructures such as an Al–Ge system , with interfaces. This recognition of a metal–semiconductor interface offers a well-regulated mechanism to produce robust and effective nanoelectronic devices.…”

Section: Introductionmentioning

confidence: 99%

Advanced Room Temperature Single-Electron Transistor of a Germanium Nanochain with Two and Multitunnel Junctions

Katkar

Gupta

Granata

et al. 2020

ACS Appl. Electron. Mater.

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The single-electron transistor (SET) has tremendous importance in the microelectronic industry on account of low-power consumption, an ultrasmall size, and a large integration prospect. The key challenge is to resolve the fabrication issues of a SET to realize a mechanically steady device with reproducible and controllable transport characteristics that operate at room temperature. Herein, we report on the realization of robust and well-controlled SET devices with at least two junctions and multijunctions using an advanced nanochain (NC) architecture of germanium nanoparticles rooted by a germanium oxide ropeway. These two-junction and multitunneling-junction (MTJ) SET devices exhibit an ideal Coulomb staircase behavior of single-electron charge transfer at room temperature and obeyed the theoretical path of increasing threshold voltage with the number of tunnel junctions. This Coulomb transistor prospects magnificent rewards of room-temperature operation, periodic Coulomb oscillations, well-controlled threshold voltage and large on/off ratios and have the potential to modernize the random access memory and digital data storage technologies.

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Coulomb blockade in monolithic and monocrystalline Al-Ge-Al nanowire heterostructures

Cited by 5 publications

References 36 publications

Al–Ge–Al Nanowire Heterostructure: From Single‐Hole Quantum Dot to Josephson Effect

Al–Ge–Al Nanowire Heterostructure: From Single‐Hole Quantum Dot to Josephson Effect

Composition Dependent Electrical Transport in Si_1−xGe_xNanosheets with Monolithic Single‐Elementary Al Contacts

Advanced Room Temperature Single-Electron Transistor of a Germanium Nanochain with Two and Multitunnel Junctions

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Coulomb blockade in monolithic and monocrystalline Al-Ge-Al nanowire heterostructures

Cited by 5 publications

References 36 publications

Al–Ge–Al Nanowire Heterostructure: From Single‐Hole Quantum Dot to Josephson Effect

Al–Ge–Al Nanowire Heterostructure: From Single‐Hole Quantum Dot to Josephson Effect

Composition Dependent Electrical Transport in Si1−xGexNanosheets with Monolithic Single‐Elementary Al Contacts

Advanced Room Temperature Single-Electron Transistor of a Germanium Nanochain with Two and Multitunnel Junctions

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Composition Dependent Electrical Transport in Si_1−xGe_xNanosheets with Monolithic Single‐Elementary Al Contacts