A. Vescan

Diamond surface-channel FET structure with 200 V breakdown voltage

An enhancement mode diamond FET using a hydrogen-terminated surface as hole conductive channel has been fabricated with 200 V gate to drain breakdown voltage. At the 8.5-/spl mu/m gate length the maximum drain current was 22 mA/mm. 90 mA/mm maximum drain current was obtained at a gate length of 3.0 /spl mu/m. Scaling to below 1 /spl mu/m gate length assuming undegraded breakdown conditions will result in a projected RF power handling capability above 6 W/mm.

High temperature, high voltage operation of diamond Schottky diode

Abstract Very high temperature operation of homoepitaxial diamond Schottky diodes is demonstrated with rectifying behaviour up to 800 C. The Schottky material is p+-Si with a chemically stabilized Si-diamond interface, leading to significantly reduced thermal activation of the reverse currents. On diamond films with low surface doping concentration 150 V breakdown voltage at room temperature is observed.

Very high temperature operation of diamond Schottky diode

For the first time, the operating temperature of a Schottky diode structure has been pushed to 1000/spl deg/C. The diode structure consists of a Si-based Schottky material deposited onto a homoepitaxial boron doped diamond surface. At high temperatures, the forward I-V characteristics are dominated by the thermionic emission (n/spl ap/1.01) across a barrier of 1.9 eV height. The reverse characteristics are still dominated by thermally activated defects. The series resistance shows thermal activation associated with the boron doping.

High-voltage Schottky diode on epitaxial diamond layer

Abstract Homoepitaxial diamond Schottky diodes with leakage current less than 10−7 A cm−2 up to the breakdown voltage of 90 V are discussed. Under forward voltage an exponential current increase over six orders of magnitude and an ideality factor of n

High-temperature, high-voltage operation of pulse-doped diamond MESFET

The fabrication and operation of a pulse-doped diamond metal-semiconductor field-effect transistor (MESFET) is presented showing a usable source drain voltage of 70 V and no breakdown up to 100 V at 350/spl deg/C operating temperature. A channel sheet concentration of 8.5/spl times/10/sup 12/ cm/sup -2/ could be fully modulated leading to a maximum transconductance of 0.22 mS/mm, although full activation of the boron acceptor had not been reached. For an optimized device structure, with reduced gate length below 0.25 /spl mu/m and full activation, more than 10 W/mm RF-power density can be predicted.

IV characteristics of epitaxial Schottky Au barrier diode on p+ diamond substrate

Abstract Epitaxial p-type Schottky barrier diodes on synthetic p+ substrates were analysed in terms of their reverse I V characteristics. A new electronic model was developed to describe the excess leakage current generally observed in epitaxial diodes. This current is attributed to homogeneously distributed defects, acting only on a small fraction of the diode surface area, bypassing the Schottky barrier contact. Passivation experiments are reported to reduce their density.

The nucleation of highly oriented diamond on silicon via an alternating current substrate bias

A new bias‐enhanced nucleation method of forming highly oriented diamond on Si(100) is reported using an alternating current bias source. The percentage of aligned particles via alternating current bias‐enhanced nucleation (ac BEN) was greater than 50%. This is compared to less than 10% highly oriented particles when using a conventional negative dc substrate bias. Based on previous work in this area, the peak negative voltage portion of the ac wave form is believed to be responsible for enhancing diamond nucleation. The positive and moderate negative voltage portion of the ac wave form appears to aid the process of forming the highly oriented diamond.

High current p/p/sup +/-diamond Schottky diode

Epitaxial p-type Schottky diodes have been fabricated on p/sup +/-substrate. While the activation energy of the epitaxial layer conductivity is 390 meV, that of the substrate is only 50 meV. At forward bias the substrate conductivity dominates above 150/spl deg/C, leading for a 5/spl times/10/sup -5/ cm/sup 2/ area contact to a series resistance of 14 /spl Omega/ at 150/spl deg/C reducing to 8 /spl Omega/ at 500/spl deg/C. To our knowledge, this is the lowest series resistance reported so far for a diamond Schottky diode enabling extremely high current densities of 10/sup 3/ A/cm and a current rectification ratio at /spl plusmn/2 V of 10/sup 5/ making these diodes already attractive as high temperature rectifiers.<<ETX>>

Electrical characterisation of diamond resistors etched by RIE

Abstract Planar homoepitaxial boron doped diamond films were grown on insulating nitrogen doped synthetic (100) oriented substrates and structured by RIE in Ar O 2 plasma into mesa-resistors. Low etch-rate etching was used to essentially remove the contact influence and profile the active layer by differential etching. Using this technique spike doping profiles in the nm thickness scale can be resolved.

Application of highly oriented, planar diamond (HOD) films of high mechanical strength in sensor technologies

Abstract Diamond possesses many characteristics of an ideal material for microsensors, and has indeed emerged as a promising candidate. In comparison to its competitors Si and SiC, large area diamond films are still polycrystalline and inhomogeneous in grain size and orientation. This still determines the material properties, and thus the sensor technology and device performance. However, highly oriented diamond films of high quality have been developed recently, using a modified bias enhanced nucleation method [1]. These films can be described by highly planar, textured surfaces, mirror like backsides, low internal stress and high mechanical strength. Conventional semiconductor processing schemes can now be fully implemented, allowing one to scale high performance micromechanical sensor structures into th lower micrometer range. In this paper, a novel concept based on selective area epitaxy (SAE), pulse doping, reactive ion etching, multilayer contacts and wet chemical backside patterning with micron resolution is presented. The elastic properties and the piezoresistive characteristics of boron doped diamond have both been investigated from diamond cantilever beam deflection measurements. For 15 μm thin HOD-films, a Youngs modulus of approximately 830 GPa has been extracted from resonance frequency measurements and nanoindentation measurements. From this data a fracture strength of σfr=2.72 GPa is calculated. To our knowledge, these data represent the highest values reported up to now for such thin films.