Piezoresistivity of Polycrystalline Diamond Films

Abstract

Polycrystalline diamond film (PDF) is known for its high power, high temperature, and radiation hard potential. The interest in piezoresistivity of PDF is that it is a candidate for high temperature sensing (e.g., pressure sensor).Piezoresistivity measurements were taken of boron-doped PDF grown by microwave-plasma chemical vapor deposition(CVD). Three substrates, silicon, aluminum nitride and tungsten were used. Films were detached from these substrates, then attached to a ceramic substrate. The piezoresistivity varies, dependent on the original host substrate. For example, at room temperature, the PDF film from tungsten has a greater gauge factor, around 75. The carrier activation energy of this film, determined from log R(l/T), was nominally 0.25eV.Combining thick film technology and CVD processes, patterned B-doped PDF has been achieved monolithically on A1N substrates. The characteristics of this configuration is being investigated and will be presented.

The pressure sensitivity of wrinkled B-doped nanocrystalline diamond membranes

“…This increase is attributed to the difference in stress in the resulting film caused by the aforementioned difference in thermal expansion coefficient of the two types of glass with respect to the thermal expansion coefficient of the diamond film. Wur and Davidson reported a similar dependence of the piezoresistivity of microcrystalline diamond films on the host substrate 17 . Dependent on whether the thermal expansion coefficient of the underlying substrate is smaller or larger than that of diamond (1 × 10 −6 °C −1 ) tensile or compressive stress, respectively, will build up in the NCD film.…”

Review on advances in microcrystalline, nanocrystalline and ultrananocrystalline diamond films-based micro/nano-electromechanical systems technologies

“…The first report of piezoresistivity in SCD and PCD films-based MEMS sensors, by researchers at Michigan State University in 1992 [202], generated substantial interest in the utilization of p-type PCD films grown by chemical vapor deposition (CVD), as a material for sensor applications, owing to its unique physical and chemical properties and potential operation at high temperatures. A number of studies focused on the piezo-resistive effect of PCD films-based sensors [203][204][205][206][207][208][209][210][211][212][213][214][215][216], such as the gauge factor as a function of operating temperature. A MEMS cantilever or diaphragm made of either Si, stainless steel or undoped PCD film, is usually used as a structural material.…”