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Ga-incorporated ZnSnAs [ABSTRACT FROM AUTHOR]

Abstract: For the purpose of investigating their structural and optical properties, GaSb thin films and GaSb/AlSb multiple quantum well (MQW) structures were grown on Si(111) substrates. A GaSb/AlSb MQW structure was also grown on Si(001) substrate as a control sample. Surface morphologies and a XRD measurements of GaSb films grown on Si(111) substrates showed that the GaSb film with a 5 nm thick AlSb initiation layer has good crystal quality. Observation of the RHEED patterns of both MQWs suggests that both GaSb films are under tensile strain at growth temperature. In-plane XRD measurement of MQW on Si(111) showed that the (111) face of the GaSb film is aligned to the Si(111) surface upon rotation by 30°. Photoluminescence (PL) spectra consisting of two peaks at 1250∼1400 nm were observed for both MQWs. [Copyright &y& Elsevier]

Abstract: We have prepared Ge0.92Mn0.08 thin films by molecular beam epitaxy (MBE) on semi-insulating (001) GaAs substrates and investigated their transport and magnetic properties. We have found out that the resulting properties of the thin films are highly dependent on the substrate temperature T s. The sample grown at T s=130°C exhibited a pronounced negative magnetoresistance and anomalous Hall effect even up to room temperature most probably due to the presence of substitutional Mn in the Ge host matrix and the formation of the Ge5Mn3 phase. Because these phenomena were not detected for samples grown above 130°C, we believe that these are due to the T s dependence of Mn distribution in Ge0.92Mn0.08 thin films and the degree of the interdiffusion of Ge, Ga and As atoms at the Ge0.92Mn0.08/GaAs interface. [Copyright &y& Elsevier]

Abstract: (Ga,Mn)As/Zn-doped GaAs superlattices (SLs) have been prepared by molecular beam epitaxy (MBE), and the effect of low-temperature thermal annealing on their structural, electrical, and magnetic properties has been investigated. The SL structures studied in this work consists of 5-periods of 20-nm (Ga,Mn)As/5-nm GaAs. In order to introduce extra holes in (Ga,Mn)As layers, the GaAs spacer layers were doped with Zn acceptor atoms. Low-temperature thermal annealing was also performed to increase the hole concentration by reducing lattice defects like Mn interstitials and As antisite defects in (Ga,Mn)As layers. As-grown SL sample showed a ferromagnetic transition temperature T C of ∼50K, and the presence of noticeable abrupt change in magnetization around ∼35K in the M–T curve which is possibly due to the rotation of in-plane uniaxial anisotropy with changing temperature. Low-temperature annealing led to an increase in T C up to 65K accompanied with a decrease in the resistivity. [Copyright &y& Elsevier]

Abstract: We report on the molecular beam epitaxy (MBE) of GaSb films and GaSb/AlGaSb multiple quantum well (MQW) structures grown on Si(111) and Si(011) substrates using an AlSb initiation layer. The structural and optical properties of the films on the different oriented Si substrates were characterized by cross-sectional transmission electron microscopy (TEM), high-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), and photoluminescence (PL) measurements. The GaSb films and the MQW structures grown on Si(011) were found to have rather rough surfaces and of poor crystallinity under the present growth condition with the AlSb initiation layer. In contrast, the films grown on Si(111) indicated a mirror surface, definite MQW structures, and HRXRD patterns. The PL emissions within the 1.3–1.5μm for the MQW structures on Si(111) and Si(011) were observed at the temperatures up to 300 and 200K, respectively. We found that the PL peak energy, around 1.5μm, of the MQW structures grown on Si(111) is almost temperature independent up to ∼120K and exhibits a smaller variation with increasing temperature compared to those of the samples grown on Si (001) substrates. In the case of the MQW on Si (011), the PL peak energy as a function of temperature showed an intermediate behavior between those grown on Si(111) and Si(001) substrates. [Copyright &y& Elsevier]