6/1/2020
Advent Diamond has been awarded Small Business Innovation Research (SBIR) Phase II grant for $750K to conduct research and development work on advancing single-crystal diamond high power diodes capable of operating at high temperature.
The possibility of laser induced variation of optical and electrical properties of conductive nanocrystalline diamond (CNCD) films has been demonstrated. The films were produced by microwave plasma chemical vapor deposition (MPCVD) from CH4:H2:N2 gas mixtures. The films were irradiated in air with 20 ns pulses of an ArF excimer laser (λ = 193 nm). It was found that low laser pulse intensity (~0.05 J/cm2), well below film surface graphitization (~0.3 J/cm2) and nanoablation (~0.08 J/cm2) thresholds, induces changes of the film properties. The effect requires multiple pulsed irradiation and results in a decrease of the film electrical conductivity, which is accompanied by optical bleaching of the diamond film absorption.
Diamond PIN diodes with an approximately 5-𝜇m thick i-layer and coated with a thin boron nitride (BN) layer have been tested with a thermal neutron beam. For a flux of 4.4 °¡ 106 n/s/cm2, count rates were on the order of 30–100 counts per second depending on the thickness of the BN neutron converter layer. Pulse height spectra showed features associated with 𝛼 and 7Li fission products consistent with the thickness of the BN layer. An irradiation test with a 1 MeV neutron equivalent fluence of 1015 n/cm2 showed no significant alteration in the count rate of the tested detector.
Fig. 3. Detector mount. The detector frames made out of printed circuit boards with
the detector centered at the tip of the frame.
A new technique for neutralizing the polarization effect of diamond detectors has been demonstrated. The technique, which relies on the diamond detector to be configured as a diode, is to periodically pulse the diamond diode with forward bias. A 210Po alpha source was used to induce the polarization effect for a thin PIN diamond radiation detector. Results show that for a single forward bias pulse, a forward current of about 60 nA applied for 1 s removes the polarization buildup. The benefits of using this technique add significant value to the diamond diode configuration.
Fig. 6. While irradiated by 210Po, the diamond diode was pulsed periodically with forward bias. The frequency of periodic forward bias pulses was changed and the results are shown. The frequencies used: 1 s out of every 24 s (black, top), 1 s out of every 192 s (red, middle), and 1 s out of every 1800 s (blue, bottom). For a constant reverse bias of 10 V (green), the polarization effect is obs...
The response of a PIN diamond diode with a 4.5 μm thick i-layer to 𝛼-particles from a 210Po radioactive source has been measured and compared to the response from a 300 μm thick single crystal type IIa diamond. The results show that this PIN diamond diode with thin i-layer can be employed to detect slow neutrons following absorption on a converter boron layer. Such a detector will operate at low voltages and be rather insensitive to gamma background and neutron radiation damage.
Fig. 6. Pulse height distributions for the response to 4.5 MeV 𝛼-particles emitted from a sealed 210 Po radioactive source. The left histogram is for a 4.5 μmPIN-doped diamond diode. The right histogram is for an undoped 300 μm single crystal diamond.
4/6/2018
Advent Diamond has been awarded a National Science Foundation (NSF) Small Business Innovation Research (SBIR) grant for $225,000 to conduct research and development work on advancing single-crystal diamond diodes capable of operating at high temperature and power.
8/24/2017
Diamonds are the overachievers of the materials world. They can sustain incredibly high temperatures and electric fields. They also conduct heat better than any other material. These properties make them ideal for very specific applications. Currently, silicon dominates the electronics market. It’s used to make everything from your cell phone computer chip and laptop processor to microwave ovens. But as versatile as silicon is, there are certain areas where it falls flat.
DIAMOND AND RELATED MATERIALS The possibility of laser induced variation of optical and electrical properties of conductive nanocrystalline diamond (CNCD) films has been demonstrated. The films were produced by microwave plasma chemical vapor deposition (MPCVD) from CH4:H2:N2 gas mixtures. The films were irradiated in air with 20 ns pulses of an ArF excimer laser (λ =193 nm). It was found that low laser pulse intensity (~ 0.05 J/cm2), well below film surface graphitization (~ 0.3 J/cm2) and nanoablation (~ 0.08 J/cm2) thresholds, induces changes of the film properties. The effect requires multiple pulsed irradiation and results in a decrease of the film electrical conductivity, which is accompanied by optical bleaching of the diamond film absorption.
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DIAMOND AND RELATED MATERIALS Cubic boron nitride (c-BN) was deposited on silicon substrates using electron cyclotron resonance microwave plasma chemical vapor deposition (ECR MPCVD) employing Ar–He–N2–H2–BF3 gas precursors at 780 °C. In situ X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM) measurements indicated that c-BN nucleated and grew on a hexagonal boron nitride (h-BN) layer that initially formed on the substrate. The minimum and maximum bias applied to the sample that yielded c-BN growth was investigated by in situ XPS. Rutherford backscattering spectrometry (RBS), elastic recoil detection (ERD), and XPS were employed to determine the chemical composition of the produced films, while XPS and in situ ultraviolet photoelectron spectroscopy (UPS) were employed to investigate the electronic structure of film surfaces. The bandgap of the c-BN films was estimated to be 6.2 ± 0.2 eV from XPS measurement...
MRS BULLETIN Diamond is a unique material that often exhibits extreme properties compared to other materials. Discovered about 30 years ago, the use of hydrogen in plasma-enhanced chemical vapor deposition (CVD) has enabled the growth and coating of diamond in film form on various substrate materials. CVD diamond research has been actively continued subsequently to develop new understanding and approaches for the growth and processing of this fascinating material. Currently, the study and development of diamond films has enabled a wide range of applications based on the combination of unique and extreme properties of diamond and the variety of film properties obtainable through tuning the microstructure, morphology, impurities, and surfaces. This issue of MRS Bulletin introduces the latest research, recent applications, and the challenges ahead for CVD diamond films.
