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Results for “Antimonide heterostructures”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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DOE OSTI2025

Epitaxial aluminum layer on antimonide heterostructures for exploring Josephson junction effects

In this study, we present results of our recent work of epitaxially-grown aluminum (epi-Al) on antimonide heterostructures, where the epi-Al thin film is grown at either room temperature or below zero °C. A sharp superconducting transition at T ∼ 1.3 K is observed in these epi-Al films. We further show that supercurrent states are realized in Josephson junctions fabricated in the epi-Al/antimonide heterostructures with mobility μ ∼ 1.0 × 10 6 cm 2 /Vs. These results clearly demonstrate we have achieved growing high-quality epi-Al/antimonide heterostructures, a promising platform for the exploration of Josephson junction effects for quantum information science and microelectronics applications.

Antimonide heterostructures↗

DOE OSTI2024

Edge majorana quasiparticles and qubits

Various embodiments described herein provide for a topological quantum computer that uses edge Majorana quasi-particles to form qubits. An inverted Indium Arsenide (InAs) and Gallium Antimonide (GaSb) heterostructure is disclosed that is a quantum spin Hall insulator. A layer of aluminum can be deposited over a nanotube that is placed across the layers of the heterostructure. Once the nanotube is removed, and a gate is formed on the heterostructure and the heterostructure is cooled so that the aluminum becomes superconducting, helical edge states are formed at the junction of the super conducting aluminum, the InAs, and the GaSb which creates a Majorana zero modes (MZMs) at zero magnetic field. The MZMs can be used to construct a topological qubit for fault-resistant topological quantum computation.

Pan, Wei↗

DOE OSTI2023

Continuous wave room temperature operation of the 2 $μ$m GaSb-based photonic crystal surface emitting diode lasers

Continuous wave room temperature operation of 2 μm GaSb-based photonic-crystal surface-emitting diode lasers has been realized. The deep etched square mesa devices showed threshold current densities of 500 A/cm 2 at 20 °C. The epi-side down mounted lasers generated above 10 mW of output power in the continuous wave regime and tens of milliwatts in pulses from the 200 × 200 μm 2 aperture. Here, the breakthrough in the device performance parameters was achieved thanks to a highly homogeneous air-pocket retaining epitaxial regrowth process optimized for a specifically designed antimonide diode laser heterostructure. The nanofabrication method utilizing low temperature atomic hydrogen surface cleaning yielded low disorder square lattice of droplet-shaped voids covered by uniform p-cladding layer. The laser emission spectrum as well as near/far field patterns demonstrated peculiar features presumably linked to deformation of the void shape during regrowth and formation of the array of filaments.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2022

Photonic Crystal Surface Emitting Diode Lasers with λ near 2 µm

Epitaxially regrown electrically pumped photonic crystal surface emitting lasers (PCSELs) operating near 2 µm were designed and fabricated within a III-V-Sb material system. A high-index-contrast photonic crystal layer was incorporated into the laser heterostructures by air-pocket-retaining epitaxial regrowth. Transmission electron microscopy studies confirmed uniform and continuous AlGaAsSb initial growth over the nano-patterned GaSb surface, followed by the development of the air-pockets. The PCSEL threshold current density had a minimal value of ~170 A/cm 2 in the 160–180 K temperature range when the QW gain spectrum aligned with the Γ 2 band edge of the photonic crystal. The devices operated in a continuous wave regime at 160 K. The divergence and polarization of the multimode laser beam emitted from the 200 µm × 200 µm PCSEL aperture were controlled by filamentation.

36 MATERIALS SCIENCE↗

DOE OSTI2025

A structural analysis of ordered Cs3Sb films grown on single crystal graphene and silicon carbide substrates

Alkali antimonides are well established as high efficiency, low intrinsic emittance photocathodes for accelerators and photon detectors. However, conventionally grown alkali antimonide films are polycrystalline with surface disorder and roughness that can limit achievable beam brightness. Ordering the crystalline structure of alkali antimonides has the potential to deliver higher brightness electron beams by reducing surface disorder and enabling the engineering of material properties at the level of atomic layers. In this report, we demonstrate the growth of ordered Cs3Sb films on single crystal substrates 3C-SiC and graphene-coated 4H-SiC using pulsed laser deposition and conventional thermal evaporation growth techniques. The crystalline structures of the Cs3Sb films were examined using reflection high energy electron diffraction and x-ray diffraction diagnostics, while film thickness and roughness estimates were made using x-ray reflectivity. With these tools, we observed ordered domains in less than 10 nm thick films with quantum efficiencies greater than 1% at 530 nm. Moreover, we identify structural features such as Laue oscillations indicative of highly ordered films. We found that Cs3Sb films grew with flat, fiber-textured surfaces on 3C-SiC and with multiple ordered domains and sub-nanometer surface roughness on graphene-coated 4H-SiC under our growth conditions. We identify the crystallographic orientations of Cs3Sb grown on graphene-coated 4H-SiC substrates and discuss the significance of examining the crystal structure of these films for growing epitaxial heterostructures in future experiments.

36 MATERIALS SCIENCE↗