Gas sensing properties of hydrogen-terminated diamond (original) (raw)
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Water adsorbate mediated accumulation gas sensing at hydrogenated diamond surfaces
Sensors and Actuators B: Chemical, 2013
Hydrogenated diamond (HD) specimens feature a peculiar form of gas response which occurs at room temperature and which is mediated by a thin layer of water that tends to accumulate on HD surfaces as these are exposed to normal atmospheric conditions. HD specimens are known to be sensitive to gases and vapours that are capable of forming acid-base reactions in liquid water. In this paper we show that HD sensors feature a novel kind of accumulating gas response which -under favourable conditions -comes close to an integrator-like behaviour. In this integrator-limit of operation, the HD gas response becomes proportional to the total flow of reactive gases that had been interacting with the water adsorbate layer on top of the HD sensors.
Gas sensing properties of nanocrystalline diamond at room temperature
Beilstein Journal of Nanotechnology, 2014
Toxic gas sensing device with metal electrodes built into nanocrystalline diamond (NCD) is investigated. The NCD morphology is controlled via seeding and/or deposition time. The surface properties and morphology of NCD are studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). AFM measurements reveal increase in NCD surface area by up to 13%. Gas sensing properties of H-terminated NCD device show high sensitivity towards oxidizing species where the surface conductivity is increased by an order of magnitude for humid air and by three orders of magnitude for COCl 2 . The surface conductivity exhibits a small decrease to reducing spices (CO 2 , NH 3 ).
Gas sensing properties of nanocrystalline diamond films
Diamond and Related Materials, 2010
Toxic gas sensing device with metal electrodes built into nanocrystalline diamond (NCD) is investigated. The NCD morphology is controlled via seeding and/or deposition time. The surface properties and morphology of NCD are studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). AFM measurements reveal increase in NCD surface area by up to 13%. Gas sensing properties of H-terminated NCD device show high sensitivity towards oxidizing species where the surface conductivity is increased by an order of magnitude for humid air and by three orders of magnitude for COCl 2 . The surface conductivity exhibits a small decrease to reducing spices (CO 2 , NH 3 ).
A polycrystalline diamond thin-film-based hydrogen sensor
Sensors and Actuators B: Chemical, 1995
A new microelectronic gas sensor utilizing polycrystalline diamond film in conjunction with a catalytic metal has been developed for hydrogen detection. The sensor is fabricated in a layered Pd/i-diamond/p-diamond metal-insulator-semiconductor (MIS) Schottky-diode configuration on a tungsten substrate. The performance of the sensor for Hz detection has been examined in the temperature range 27-300 "C. The analysis of the steady-state reaction kinetics has confirmed that the hydrogen adsorption process is responsible for the barrier-height change in the diamond-based MIS Schottky diode. The use of diamondfilm technology opens the door to the development of a microelectronic gas sensor that can operate at a wider and higher temperature range than the ones based on present silicon technology.
Diamond Microelectronic Gas Sensors
Proceedings of the International Solid-State Sensors and Actuators Conference - TRANSDUCERS '95
Diamond-based microelectronic gas sensors using plasma enhanced chemical vapor deposition (PECVD) technology have been explored in our laboratory. This paper presents a new gas sensor using Pal/i-diamond/p-diamond structure for hydrogen detection. Hydrogen sensitivity of the device has been characterized and analyzed as a function of hydrogen partial pressure and temperature by using current-voltage (l-V) and capacitance-voltage-frequency (C-V-F) methods. The hydrogen sensitivity is high, reproducible, and repeatable over a wide temperature range including room temperature.
IEEE Transactions on Electron Devices, 1999
This paper presents the results from analysis and modeling of the gas sensing performance, current conduction and gas detection mechanisms, and adsorption effects on device parameters of a Pt/SnOx x x/diamond-based gas sensor. The sensor is sensitive and demonstrates high, repeatable, and reproducible reaction. The sensor response in seconds to small concentrations of O2, CO, and H2 gases. The current conduction mechanism of the diamond-based CAIS (catalyst/adsorptive-oxide/intrinsicdiamond/semiconductor-diamond) diode was found to be dominated by space charge limited conduction in the forward bias region and tunneling in the reverse bias region, distinctively different from silicon based sensors. While gas adsorption causes a change in the barrier height and tunneling factor, no significant change was observed in the ideality factor over the temperature range investigated. The detection mechanism of the sensor is attributable to the change in occupancy ratio of the oxygen vacancies of the adsorptive oxide layer upon oxygen exposure, increasing the contact potential between adsorptive-oxide and intrinsic-diamond.
Fabrication of diamond nanorods for gas sensing applications
Applied Surface Science, 2010
Diamond nanorods were fabricated for a sensing device by utilizing reactive ion etching in CF 4 /O 2 radio frequency plasma. The length of the nanorods has been controlled by the ion etching time. The obtained morphologies were investigated by scanning electron microscopy. The gas sensing properties of the Hterminated diamond-based sensor structures are indicating that we have achieved high sensitivity to detect phosgene gas. Also, our sensor exhibited good selectivity between humid air and phosgene gas if the measurement is conducted at elevated temperatures, such as 140 • C. Furthermore, such sensor response rating could reach as high value as 4344 for the phosgene gas, which was evaluated for the sample consisting of the longest nanorods (up to 200 nm).
High Temperature Surface Conductivity of Hydrogenated Diamond Films Exposed to Humid Air
Acta Physica Polonica A, 2010
Surface conductivity of thin diamond films was measured as a function of temperature up to 450 • C. Hydrogenated diamond was synthesized by chemical vapor deposition in hydrogen/carbon plasma. Low values of charge carrier activation energy (≈ 10 meV) were observed, when hydrogenated diamond films were exposed to the ambient humid air. However, the activation energy increased by two orders of magnitude as film temperature exceeded 300 • C. We have attributed this behavior to the desorption of the H2O adlayer. The jump of the activation energy did not occur, when experiment was performed in vacuum. We have also shown that donor doping leads to the up-shift of the Fermi level much above the acceptor-like band gap levels induced by surface C-H bonds, which cannot be compensated by transfer of electrons from diamond to the double H-H2O layer.
physica status solidi (a), 2006
In this work (100) diamond films are hydrogenated using a conventional MWPE-CVD (microwave plasma enhanced chemical vapour deposition) reactor containing a H 2 or a H 2 /O 2 mixture. For the latter, XPS (X-ray Photoelectron Spectroscopy) experiments show an increased presence of oxygen at the (sub)surface. Contrary to pure H 2 -plasma treated samples, H 2 /O 2 -treated layers still posses enough conductivity to enable STS (Scanning Tunneling Spectroscopy) investigations to be carried out after an annealing at 410 °C in UHV (Ultra High Vacuum). Evidence for surface resonance states is detected, yielding a possible explanation for the measured conductivity. UPS (UV Photoelectron Spectroscopy) data point to a negative electron affinity of -0.3 eV for the H 2 /O 2 -treated layers.