The growth of Zn1‐xMgx Sey Te1‐y layers was performed on (100) ZnTe substrate by metalorganic vapour phase epitaxy using dimethylzinc, bis‐methylcyclopentadienyl‐magnesium, diethyltelluride and diethylselenide. The effects of substrate temperature upon the compositions of Mg and Se have been investigated. The Mg composition in Zn1‐xMgx Sey Te1‐y layer is significantly enhanced at low substrate temperature. Although the Se composition decreases with decreasing the substrate temperature, Zn1‐xMgx Sey Te1‐y layer with a relatively high Se composition of 0.3 is obtainable at a low substrate temperature as low as 380 ºC. For all the layers, a two‐mode behaviour with ZnTe‐ and MgTe‐like longitudinal optical phonon modes is confirmed by Raman scattering. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The fabrication of double-barrier resonant tunneling diodes (DBRTDs) using γ-Al2O3/epitaxial-Si heterostructures with different well thicknesses and different barrier thicknesses was studied. Current–voltage characteristics of the DBRTDs were investigated to determine the relationships between the peak-to-valley current ratio and the quantum well thickness, and between the peak current density and the barrier thickness for the maximum peak-to-valley current ratio (PVCR) at room temperature. In this study, we confirmed a maximum peak-to-valley current ratio of 26 at room temperature with a quantum well (epi-Si) thickness of 3 nm and a barrier (γ-Al2O3) thickness of 2 nm. A comparison between the theoretical and experimental peak voltage positions for a negative differential resistance was performed, indicating good agreement. A lower peak current density of few mA/cm2 was obtained.

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Introduction For future LSI applications, it has been proposed to replace the traditional SiO 2 with the high-k materials such as Al 2 O 3 , ZrO 2 , HfO 2 , Si 3 N 4 and Y 2 O 3 for gate dielectrics. In our laboratory, crystalline γ-Al 2 O 3 films have been studied and grown on Si substrate successfully using a hybrid source MBE [1]. It has a number of applications in Si devices such as quantum well devices and silicon-on-insulator technology [2]. The electrical properties of the γ-Al 2 O 3 have been reported [3], which describes no SiO 2 interface layer between Si and Al 2 O 3 , high breakdown field comparable with SiO 2 , and low leakage current compared with other insulators. Therefore, crystalline γ-Al 2 O 3 films were expected as an attractive candidate for high-k materials. However, evaluations of crystalline γ-Al 2 O 3 films might be not enough for several applications. Because crystalline films usually have crystal defects or grain boundaries, which may have a bad influence on the characteristics. In this report, we evaluated the influence of crystal defects or grain boundaries by comparison of breakdown voltage among conductive AFM's cantilevers and MIS structures that has several electrode sizes. Furthermore, we fabricated n-channel MISFETs with Aluminum gates using the crystalline film as gate dielectrics and confirmed good characteristics.