Non-metalin situandex situohmic contacts to n-ZnSe

Schüll, K.; Spahn, W.; Hock, V.; Lunz, U.; Ehinger, M.; Faschinger, W.; Landwehr, G.

doi:10.1088/0268-1242/12/4/026

Cited by 4 publications

(2 citation statements)

References 18 publications

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“…The 400-mmthick GaAs substrates are n-doped with Si concentrations of 3 3 10 16 cm 23 and back-contacted with indium. ZnSe epilayers, grown on the substrates by molecular beam epitaxy, are n-doped with Cl donors and transparently contacted by 40 nm of indium tin oxide 11 . The epilayers are 100, 150, 200 and 300 nm thick and have a carrier density of 5±15 3 10 17 cm 23 ; for brevity, only results from two extreme samples (100 nm thick, n 5 3 10 17 cm 23 and 300 nm thick, n 15 3 10 17 cm 23 ) will be presented.…”

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confidence: 99%

Persistent sourcing of coherent spins for multifunctional semiconductor spintronics

Malajovich

Berry

Samarth

et al. 2001

Nature

216

104

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Recent studies of n-type semiconductors have demonstrated spin-coherent transport over macroscopic distances, with spin-coherence times exceeding 100 ns; such materials are therefore potentially useful building blocks for spin-polarized electronics ('spintronics'). Spin injection into a semiconductor (a necessary step for spin electronics) has proved difficult; the only successful approach involves classical injection of spins from magnetic semiconductors. Other work has shown that optical excitation can provide a short (<500 ps) non-equilibrium burst of coherent spin transfer across a GaAs/ZnSe interface, but less than 10% of the total spin crosses into the ZnSe layer, leaving long-lived spins trapped in the GaAs layer (ref. 9). Here we report a 'persistent' spin-conduction mode in biased semiconductor heterostructures, in which the sourcing of coherent spin transfer lasts at least 1-2 orders of magnitude longer than in unbiased structures. We use time-resolved Kerr spectroscopy to distinguish several parallel channels of interlayer spin-coherent injection. The relative increase in spin-coherent injection is up to 500% in the biased structures, and up to 4,000% when p-n junctions are used to impose a built-in bias. These experiments reveal promising opportunities for multifunctional spin electronic devices (such as spin transistors that combine memory and logic functions), in which the amplitude and phase of the net spin current are controlled by either electrical or magnetic fields.

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confidence: 99%

Persistent sourcing of coherent spins for multifunctional semiconductor spintronics

Malajovich

Berry

Samarth

et al. 2001

Nature

216

104

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“…In case of all ex situ techniques, contacts at the metal-ZnSe interface are hampered by the formation of a native oxide. X-ray photoelectron spectroscopy studies performed in ref identified this native oxide as a thin SeO 2 layer on top of the ZnSe surface. So far in the literature, the lowest ρ c was reported for a layer stack of Ti/Pt/Au contacts, for which the oxide was wet-chemically removed prior to metallization.…”

Section: Resultsmentioning

confidence: 97%

Low-Temperature Ohmic Contacts to n-ZnSe for all-Electrical Quantum Devices

Janssen

Hartz

Huckemann

et al. 2020

ACS Appl. Electron. Mater.

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The II/VI semiconductor ZnSe is an ideal host for novel devices for quantum computation and communication as it can be made nuclear-spin free to obtain long electron spin coherence times, exhibits no electron valley-degeneracy, and allows optical access. A prerequisite to electrical quantum devices is lowresistive Ohmic contacts operating at temperatures below 10 K, which have not been achieved in ZnSe yet. Here, we present a comprehensive study on the realization of Ohmic contacts to ZnSe by three different technological approaches, ion implantation of halogen donors, epitaxial doping with in situ contact processing, and finally, a unique ZnSe regrowth technique. The latter allows fabrication of Ohmic contacts with local doping that can be used to connect to a buried conducting channel such as those used in unipolar devices. DC measurements revealed high contact resistivity for Ohmic contacts to ZnSe doped via halogene ion implantation, while in situ aluminum (Al) contacts on epitaxially chlorine-doped ZnSe yield record low contact resistivities in the order of 10 −5 Ω cm 2 even at cryogenic temperatures. Finally, making use of the regrowth technique, local Ohmic contacts to ZnSe are demonstrated, which still feature low contact resistivities of (1.4 ± 0.4) × 10 −3 Ω cm 2 at 4 K. These findings pave the way for new electrical devices in the ZnSe material system such as field-effect transistors, electrostatically defined qubits, or quantum repeaters operating at cryogenic temperatures.

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