Dielectric Properties of Zinc Oxide Sensing Film With Nitrogen Doped in Capacitance Relative Humidity Sensor

A capacitance humidity sensor with a nitrogen-doped zinc oxide (N-doped ZnO) sensing film has been completed in this research. The N-doped ZnO material serves as a semiconductor sensing film with the Hall type of hole carriers (p-type). The carrier concentration and carrier mobility of p-type N-doped ZnO sensing films of capacitance humidity sensors without a polymer buffer layers are, respectively, 7.18
$\times 10^{{15}}$
cm
$^{-{3}}$
and 3.69
$\times 10^{{2}}$
cm
²
/
$\text{V}\,\cdot$
s. Besides, the carrier concentration and carrier mobility of p-type N-doped ZnO sensing films of capacitance humidity sensors with a polymer buffer layer are, respectively,
$\vphantom {_{\int }}\,\,1.06\,\,\times 10^{{18}}$
cm
$^{-{3}}$
and 3.34
$\times 10^{{2}}$
cm
²
/
$\text{V}\,\cdot$
s. The electrical resistivity of sensing films without and with the buffer layer reaches 4
$\times 10^{{2}}$
and 8
$\times 10^{-{2}}\,\,\Omega $
-cm, respectively. In the measurements of the moisture adsorption and desorption processes, the dielectric constant of the capacitance humidity sensor without a buffer layer exhibits a capacitance effect of about 460 nF/m. The sensitivity of 45 pFm
$^{-{1}}$
/%RH for the relative humidity measurement of N-doped ZnO sensing films at the upper electrode terminal of the capacitance humidity sensor with a polymer buffer layer is also obtained.