Growth variations and scattering mechanisms in metamorphic In0.75Ga0.25As/In0.75 Al0.25As quantum wells grown by molecular beam epitaxy

On‐Chip Andreev Devices: Hard Superconducting Gap and Quantum Transport in Ballistic Nb–In0.75Ga0.25As‐Quantum‐Well–Nb Josephson Junctions

“…The In 0.75 Ga 0.25 As/In 0.75 Al 0.25 As/GaAs quantum wells [7] used in this study were grown by MBE. The wafer as shown in Figure 1a from the bottom to the surface comprises a 500 µm GaAs substrate, 50, 75, and 250 nm buffer layers of GaAs, AlAs, and GaAs, a 1300 nm InAlAs step-graded buffer layer, a 250 nm InAlAs buffer layer, a 30 nm 2DEG consisting of an In 0.75 Ga 0.25 As quantum well with electron density n s = 2.24 × 10 11 (cm −2 ) and mobility µ e = 2.5 × 10 5 (cm 2 V −1 s −1 ) in the dark and n s = 2.28 × 10 11 (cm −2 ) and µ e = 2.58 × 10 5 (cm 2 V −1 s −1 ) after illumination.…”

“…The 2DEG quantum well is covered by a 60 nm In 0.75 Al 0.25 As spacer, 15 nm of n-type modulation doped In 0.75 Al 0.25 As, and a 45 nm In 0.75 Al 0.25 As layer followed by a 2 nm InGaAs cap layer. [7] Using photolithography and wet etching, in which a sulfuric acid solution of compositions H 2 SO 4 , H 2 O 2 , and H 2 O was used, we created an active region (a raised area referred to as mesa structure) with length l′ = 1440 and w′ = 160 µm in the middle of our chip where all the eight identical junctions are patterned and fabricated (see Figure 1b).…”

“…[7] In addition to all these advantages, the ability to tune the indium composition allows the formation of highly transmissive metal-semiconductor interfaces which we discuss in this paper. We study the fabrication and low-temperature measurements of eight symmetric S-Sm-S planar and ballistic Josephson junctions on a chip containing an In 0.75 Ga 0.25 As quantum well in a heterostructure in which each junction consists of two identical niobium (Nb) superconducting electrodes in contact with a 2DEG that is formed ≈120 nm below the wafer's surface.…”

High mobility In0.75Ga0.25As quantum wells in an InAs phonon lattice

“…Temperature-dependent transport models have been developed on InGaAs QWs [21] and InGaAs heterostructures [22]. In this work, the scattering from background impurities is added as it is the dominant scattering mechanism at low carrier densities in In 0.75 Ga 0.25 As/In 0.75 Al 0.25 As QWs [12]. Scattering from acoustic phonon, polar optical phonon, background impurity, modulation doping, interface roughness and alloy disorder were considered here based on the work of Gold [23] and Price [24].…”

Análise da estrutura energética e da dinâmica de portadores fotogerados em heteroestruturas semicondutoras de InGaAs/InP e AlGaAs/GaAs

“…63 Diferentes valores de potenciais por AD em ligas de InGaAs, o qual define a taxa de espalhamento por AD, foram recentemente reportados: 0.7 eV, 64 0.5 eV, 12 e 0.2 eV. 65 Os dados experimentais implicam o papel dominante do espalhamento por IR, nesse caso, a escolha do potencial por AD é insignificante e nossos cálculos foram realizados com o valor 0.7 eV. Utilizando os dados mostrados na Figura 34, a variação da mobilidade de elétrons com a densidade de carga foi apresentada na Figura 36, onde a dependência da mobilidade com a densidade foi calculada para espalhamento por AD (linha tracejada) e espalhamento por AD+IR (linha contínua), ambas usando um perfil de potencial TQW.…”