Ferroelectric Pb0.9La0.1Zr0.2Ti0.8O3 thin film capacitors with a symmetrical La-Sr-Co-O top and bottom electrodes have been grown on [001] Si with yttria stabilized zirconia (YSZ) buffer layer. A layered perovskite ‘‘template’’ layer (200–300 Å thick), grown between the YSZ buffer layer and the bottom La-Sr-Co-O electrode, is critical for obtaining the required orientation of the subsequent layers. When compared to the capacitors grown with the Y-Ba-Cu-O top and bottom electrodes, these structures possess two advantages: (i) the growth temperatures are lower by 60–150 °C; (ii) the capacitors show a larger remnant polarization ΔP (ΔP=switched polarization–nonswitched polarization), 25–30 μC/cm2, for an applied voltage of only 2 V (applied field of 70 kV/cm). The fatigue, retention, and aging characteristics of these new structures are excellent.

Ion milling has been used to convert molecular beam epitaxy vacancy-doped CdxHg1−xTe from p- to n-type. Electron beam induced current and remote electron beam induced current (REBIC) measurements have been performed to study the pn junction depth and lateral extension dependence on the milling time, milling current, and vacancy concentration. The conversion depth is linear with the milling time and current and inversely proportional to the vacancy concentration in layers thinner than 10 μm. This shows that filling of Hg vacancies in this region during conversion is limited by the rate of supply of extra Hg from the milling. The lateral extension also increases linearly with the milling time, the ratio of the lateral extension to the depth being ∼0.5. One can therefore use REBIC on the top surface to determine the junction depth, which greatly simplifies the measurement and does not destroy the diodes.

The authors present a systematic study showing the evolution of the defect morphology and crystalline quality in molecular beam epitaxially grown HgTe epilayers with substrate temperature. The authors have characterized the layers using optical microscopy, atomic force microscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, and high-resolution x-ray diffraction. Four types of defects (microvoids, circular voids, hillocks, and high-temperature voids) have been characterized on epilayers grown in the substrate temperature range of 183.3–201.3 °C. The authors find that there is a minimum in the area covered by defects at a temperature just below the onset of Te precipitation, and they define this temperature as the optimal growth temperature. Above the optimal growth temperature the authors observe the appearance of high-temperature voids. By determining the onset of Te precipitation in HgTe, and performing thermodynamic calculations, the authors can also successfully predict the onset of Te precipitation in CdHgTe, which again is related to the optimal growth temperature in CdHgTe. Furthermore, the authors have found that the shape and density of the microvoids are particularly sensitive to the substrate temperature, and that these properties can be used to determine the deviation from the optimal growth temperature. From the shape and density of microvoids in one growth of HgTe, the authors can therefore determine the temperature correction needed to reach the optimal growth temperature for CdHgTe. The authors also suggest a mechanism for the formation of the microvoids based on the assumption of impurities on the substrate combined with a preferential Te diffusion in the [1 ¯11] direction across the steps.

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A systematic study of the evolution of the defect morphology and crystalline quality in molecular beam epitaxially grown CdxHg1−xTe epilayers with growth temperature is presented. The layers were characterized with optical microscopy, atomic force microscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, and high-resolution x-ray diffraction. Four types of defects (microvoids, hillocks, high-temperature voids, and needles) were characterized on epilayers grown in the growth temperature range 188.9−209.9 °C. There is a minimum in the area covered by defects at a temperature just below the onset of Te precipitation, which is defined as the optimal growth temperature. Microvoids with various shapes, and at various stages of growth, were observed side-by-side in many of the CdxHg1−xTe layers, along with hillocks and needles. The defect density of microvoids changes by several orders of magnitude in the studied temperature range. A mechanism for the formation of microvoids and needles is suggested. High-temperature voids associated with Te precipitates appear above the optimal growth temperature. The onset of Te precipitation is well described by a thermodynamic model.