Mark Arendt

Effects of NH3 nitridation on oxides grown in pure N2O ambient

Effects of NH3 nitridation on the chemical and electrical properties of N2O oxides have been studied. Compared with NH3‐nitrided SiO2, NH3 nitridation does not degrade the electrical properties of N2O oxides, thus resulting in superior impurity diffusion barrier properties, while preserving excellent interface immunity to hot‐carrier injection and much lower charge trapping. Correlation studies between the chemical and electrical properties of NH3‐nitrided N2O and NH3‐nitrided SiO2 have been done to explain these results.

Comparison of the chemical structure and composition between N2O oxides and reoxidized NH3‐nitrided oxides

The chemical structure and composition of ultrathin N2O oxides have been investigated using angle resolved x‐ray photoelectron spectroscopy and compared to those of reoxidized NH3‐nitrided SiO2. It is found that N2O oxide shows a second nitrogen‐related bond (N—O bonds) in close proximity to the SiO2/Si interface in addition to the typically observed Si—N bonds in reoxidized NH3‐nitrided SiO2. In addition, the change of the difference between Si 2p and O 1s binding energies in the N2O oxide and reoxidized NH3‐nitrided SiO2 with the take‐off angle is negligible due to the interfacial nitrogen incorporation.

Environmental reactivity characteristics of copper-oxide superconductors

Although it is known that some of the high‐Tc phases react rapidly with water, CO2, CO, and acids, no systematic comparison of the relative reactivities of the various cuprate superconductors is available. In this letter, x‐ray powder diffraction, scanning electron microscopy, x‐ray photoemission spectroscopy, and electrochemical measurements are utilized to establish a comprehensive comparison of the intrinsic reactivity characteristics of the common copper‐oxide superconductors. Consequently, the following reactivity scale has been determined: YBa2Cu3O7≳Tl2Ba2Ca2Cu3O10≳Bi2Sr2CaCu2O8 ≥La1.85Sr0.15CuO4 ≳Nd1.85Ce0.15CuO4≳Nd1.85Th0.15CuO4.

Effects of illumination during anodization of porous silicon

The effects of illumination during anodic etching of porous Si have been studied. For a fixed current density and anodization time, it has been observed that below a critical irradiance level, increasing the radiant flux density during anodization results in higher photoluminescence and a blue shift of the photoluminescence spectra. For irradiance above the critical value, the photoluminescence intensity decreases. Transmission Fourier-transform infrared spectroscopy, x-ray photoelectron spectroscopy and atomic force microscopy have been employed to investigate the effects of illumination on the characteristics of porous Si.

Environmental degradation properties of YBa2Cu3O7−δ and Y0.6Ca0.4Ba1.6La0.4Cu3O7−δ thin film structures

Abstract Utilization of the high temperature superconductor, YBa 2 Cu 3 O 7−δ , in commercial applications is becoming increasingly feasible. Before full advantage of this material can be taken, however, the lifetime, oxygen stability and processability of this ambient reactive superconductor must be improved. Corrosion resistance of YBa 2 Cu 3 O 7−δ and a cation substituted compound, Y 0.6 Ca 0.4 Ba 1.6 La 0.4 Cu 3 O 7−δ , were studied and their lifetimes in aqueous environments were determined. Results indicate a dramatic enhancement in the stability against environmental degradation for the cation substituted phase. Important mechanistic factors responsible for the enhanced corrosion resistance of the substituted phase over the parent compound are discussed.

Study of the Structure and Chemical Nature of Porous Si and Siloxene by STM, AFM, XPS, and LIMA

In situ scanning tunneling microscopy (STM) and ex situ atomic force microscopy (AFM) were used to examine the surface morphology of anodized p-Si(100) electrodes in F - -containing solutions. In addition to the formation of a mainly pitted and rough surface, in situ STM observation of anisotropic etching of Si(100) in dilute (1%) HF showed the formation of well-defined features, such as peninsulas, a 27 nm wide V-groove, and many protruding 5 nm wide micropyramids. High-resolution in situ STM resolved atomic features at the V-groove limiting (111) facets. Although this slightly etched Si sample contained no quantum pillars, it luminesced orange under UV irradiation, in the same way as a porous Si layer prepared by anodization in a more concentrated HF (1:1 HF:EtOH) solution

A New Single Source Precursor Approach to Gallium and Aluminum Nitride

Single source precursors which contain preformed gallium-nitrogen and aluminum-nitrogen bonds are being considered for the growth of gallium and aluminum nitride because of their potential for overcoming problems associated with conventional precursors. Presented is the evaluation of dimethylgallium azide, Me 2 GaN 3 (1) , bisdimethylamidogallium azide, (Me 2 N) 2 GaN 3 (2) , and bisdimethylamidoaluminum azide, (Me 2 N) 2 AlN 3 (3) as potential precursors for A1N and GaN film growth. The compounds were evaluated for stability, ease of transport, temperature of decomposition and quality of film deposited. Amorphous thin films of GaN with a band gap of 3.4 eV were deposited with 2 at 250 °C. Increasing the substrate temperature to 580 °C resulted in the deposition of epitaxial GaN films. Polycrystalline A1N films were grown with 3 at 600 °C.

Characterization of thin Chemical/Native Oxides on Si (100) by Auger and Angle-Resolved XPS

Chemical/native oxides grown on Si(100) after several standard wet cleans are characterized by Angle-resolved X-ray Photoelectron Spectroscopy (ARXPS), and Auger Electron Spectroscopy using sputter depth profiles. Target Factor Analysis (TFA) was used to separate the Si LVV Auger peak into three components identified by their lineshapes and positions as Si, SiO 2 , and SiO x - Auger depth profiles were used to quantify the thickness of the oxides, the depth distribution, and amount of SiO x in the interface region. ARXPS was used to study the chemical state distribution in the native oxides as a function of depth. The depth distribution function from the Auger data was converted to an angle-resolved format for direct comparison to the angle-resolved XPS data. With this comparison, the SiO x lineshape is correlated to a 3:1 mixture of Si 3+ and Si 2+ oxidation states.