Ion-Implanted Epitaxially Grown Gd2O3 on Silicon with Improved Electrical Properties

The effects of nitrogen incorporation by high-dose ion implantation in epitaxial gadolinium oxide (Gd2O3) films on Si (111) followed by annealing have been investigated. The nitrogen content in the oxide layer was changed by altering the implantation dose. The presence of nitrogen incorporation on the Gd2O3 layer was studied using Auger electron spectroscopy. Nitrogen incorporation is believed to occur by filling the oxygen vacancies or by removing hydroxyl group ions in Gd2O3. A maximum concentration of 11% was obtained for nitrogen in the interface between the silicon dioxide and Gd2O3 layer and the implanted areas of the Gd2O3 oxide layer after sputter depth profiling. The nitrogen distribution in the layer was found to be non-uniform. Nitrogen incorporation sharply reduced the leakage current and effectively suppressed the hysteresis. Leakage current was two orders lower compared with the pure Gd2O3. © 2020, The Author(s)

Metal semiconductor metal photodiodes based on all-epitaxial Ge-on-insulator-on-Si(111), grown by molecular beam epitaxy

We report on the fabrication and characterisation of an all-epitaxial Germanium-on-Insulator (GOI) Metal-Semiconductor-Metal (MSM) photodetector. The MSM photodetector is fabricated on a (111)-oriented epitaxial Ge layer, grown on an epitaxial Gd 2 O 3 /Si(111) substrate, by molecular beam epitaxy (MBE). The first step is the growth of the 15-nm thick Gd 2 O 3 epitaxial layer over CMOS-grade silicon, atop which an epitaxial layer of Ge is grown. Near infrared (NIR) MSM photodetectors have been fabricated over the Ge epitaxial layer with an inter-digitated (IDT) contact structure, with an active area of 100 μm x 124 μm. For the particular IDT dimensions, the dark current has been measured to be 475 μA. A responsivity of ∼ 2 mA/W is observed at a-5V bias, when excited at 1550 nm. © 2019 SPIE

Characterisation of the effectiveness of carbon incorporation in SiGe for the elimination of parasitic energy barriers in SiGe HBT's

An electrical method is applied to SiGe and SiGeC HBTs to extract the bandgap narrowing in the base layer and to characterise the presence of parasitic energy barriers in the conduction band, arising from transient enhanced boron diffusion from the SiGe layer. It is shown that a background carbon concentration with the base of approximately 1E20cm-3 eliminates parasitic energy barriers at the C/B junction and hence shows that transient enhanced diffusion of boron from the base has been completely suppressed

Te covered Si(001): a variable surface reconstruction

At a given temperature, clean and adatom covered silicon surfaces usually exhibit well-defined reconstruction patterns. Our finite temperature ab-initio molecular dynamics calculations show that the tellurium covered Si(001) surface is an exception. Soft longitudinal modes of surface phonons due to the strongly anharmonic potential of the bridged tellurium atoms prevent the reconstruction structure from attaining any permanent, two dimensional periodic geometry. This explains why experiments attempting to find a definite model for the reconstruction have reached conflicting conclusions.Comment: 4 pages, 3 gif figure

Microflares and the Statistics of X-ray Flares

This review surveys the statistics of solar X-ray flares, emphasising the new views that RHESSI has given us of the weaker events (the microflares). The new data reveal that these microflares strongly resemble more energetic events in most respects; they occur solely within active regions and exhibit high-temperature/nonthermal emissions in approximately the same proportion as major events. We discuss the distributions of flare parameters (e.g., peak flux) and how these parameters correlate, for instance via the Neupert effect. We also highlight the systematic biases involved in intercomparing data representing many decades of event magnitude. The intermittency of the flare/microflare occurrence, both in space and in time, argues that these discrete events do not explain general coronal heating, either in active regions or in the quiet Sun.Comment: To be published in Space Science Reviews (2011

High-k-oxide/silicon interfaces characterized by capacitance frequency spectroscopy

Electron capture into insulator/silicon interface states is investigated for high-k dielectrics of Gd2O3 preparedby molecular beam epitaxy (MBE) and atomic layer deposition (ALD), and for HfO2 prepared byreactive sputtering, by measuring the frequency dependence of Metal Oxide Semiconductor (MOS) capacitance.The capture cross sections are found to be thermally activated and to increase steeply with theenergy depth of the interface electron states. The methodology adopted is considered useful for increasingthe understanding of high-k-oxide/silicon interfaces

High-k-oxide/silicon interfaces characterized by capacitance frequency spectroscopy

Electron capture into insulator/silicon interface states is investigated for high-k dielectrics of Gd2O3 prepared by MBE and ALD, and for HfO2 prepared by reactive sputtering, by measuring the frequency dependence of MOS capacitance. The capture cross sections are found to be thermally activated and to increase steeply with the energy depth of the interface electron states. The methodology adopted is considered useful for increasing the understanding of high-k-oxide/silicon interfaces