Effects of molecular contamination and sp2^2 carbon on oxidation of (100) single-crystal diamond surfaces

The efficacy of oxygen (O) surface terminations of specific moieties and densities on diamond depends on factors such as crystallinity, roughness, and crystal orientation. Given the wide breadth of diamond-like materials and O-termination techniques, it can be difficult to discern which method would yield the highest and most consistent O coverage on a particular subset of diamond. We first review the relevant physical parameters for O-terminating single-crystalline diamond (SCD) surfaces and summarize prior oxidation work on (100) SCD. We then report on our experimental study on X-ray Photoelectron Spectroscopy (XPS) characterization of (100) diamond surfaces treated with oxidation methods that include wet chemical oxidation, photochemical oxidation with UV illumination, and steam oxidation using atomic layer deposition. We describe a rigorous XPS peak-fitting procedure for measuring the functionalization of O-terminated samples and recommend that the reporting of peak energy positions, line shapes, and full-width-half-maximum values of the individual components, along with the residuals, are important for evaluating the quality of the peak fit. Two chemical parameters on the surface, sp$^2$ C and molecular contaminants, are also crucial towards interpreting the O coverage on the diamond surface and may account for the inconsistency in prior reported values in literature

INVESTIGATION OF UNIFIED TABLE AND ANALYTICAL DEVICE MODELS FOR ACCURATE CIRCUIT SIMULATION

The modeling of semiconductor device characteristics using unified table and analytical models for application to circuit simulation has been studied. A unified model consists of an analytical model which has some of its operating voltages scaled by interpolated tables and some of its parameters represented by interpolated tables. The applications of unified models include the accurate modeling of the currents, conductances, charges and capacitances of semiconductor devices. The applications emphasized in this study deal with modeling the small-geometry MOS transistor. Special considerations were identified so that the unified models could produce monotonic device characteristics. The unified model technique has been implemented into a circuit simulator which does transient simulation. The circuit simulator also has the capability of using analytical models and table models for the representation of semiconductor devices. The development of a unified model for a particular device characteristic is under the software users control by using a table and parameter extraction program. The third software program developed does the numerical simulation of the MOS transistor in two dimensions. This program was used to generate current, capacitance and charge data for use with unified models in the extraction and circuit simulation programs. Measured device characteristics for the current were also used in this study of unified models

Development of plasma nanomanufacturing workcell

Plasma processing is an important technology, which provides a capability to modify the material surface through etching, deposition, activation, functionalization, polymerization, etc. In the current plasma process, the reactive area of the sample is relatively large and thus a mask is needed for selectively treating the sample surface. As a result, the whole fabrication process has become more complicated. In this paper, a plasma integrated nanomanufacturing workcell, which consists of a microplasma source and an integrated atomic force microscopy (AFM) probe tip, has been developed to improve the current plasma apparatus design. The miniature microwave plasma discharge applicator is capable of creating a miniature plasma stream with a diameter ranging from 2 mm down to micrometers. Hence, with the new plasma apparatus it has become possible to locally treat a small area of the sample surface and simplify the fabrication process as the photomask is not required. Additionally, the AFM active probe can be precisely positioned on a desired surface to inspect and manipulate nanoobjects. Here, we report the design and implementation of this new system. Experimental results demonstrate the effectiveness of the system and show that the microplasma can be used in various applications including localized etching of silicon and diamond and localized patterning of photoresist. Copyright © 2010 by ASME.Link_to_subscribed_fulltex

Barrier-Layer Optimization for Enhanced GaN-on-Diamond Device Cooling

GaN-on-diamond device cooling can be enhanced by reducing the effective thermal boundary resistance (TBReff) of the GaN/diamond interface. The thermal properties of this interface and of the polycrystalline diamond grown onto GaN using SiN and AlN barrier layers as well as without any barrier layer under different growth conditions are investigated and systematically compared for the first time. TBReff values are correlated with transmission electron microscopy analysis, showing that the lowest reported TBReff (similar to 6.5 m(2) K/GW) is obtained by using ultrathin SiN barrier layers with a smooth interface formed, whereas the direct growth of diamond onto GaN results in one to two orders of magnitude higher TBReff due to the formation of a rough interface. AlN barrier layers can produce a TBReff as low as SiN barrier layers in some cases; however, their TBReff are rather dependent on growth conditions. We also observe a decreasing diamond thermal resistance with increasing growth temperature