Porous Semiconductors Silicon and Other

Poor linearity of operating characteristics can be added to the disadvantages of porous semiconductor-based RH sensors (see Fig. 18.8). Research carried out by O Halloran et al. (1999) showed that this parameter of humidity sensors can be improved by changing the current density used to form the porous layer. It has been shown that it is possible to form a device that is linear over the humidity range 10-90 % RH. However, porous silicon layers formed at such low current density values show a long response time and poor sensitivity in comparison to layers formed using higher values of current density. 

Xu et al. (2005) believed that the fast response to humidity of Si-NPPA sensors might be due to the regular morphology and suitable thickness of the sensing layer. 

It should be noted that in each case mentioned, reduced hysteresis is mostly based on a smaller amount of condensed water (Bjorkqvist et al. 2006). In a capacitive-type sensor, this also means lower 

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