Frequency domain analysis of pyroelectric response in silicon-doped hafnium oxide (HfO2) thin films

The pyroelectric response of polycrystalline, Si-doped HfO2 layers with a thickness of 20 nm is investigated in a frequency range of 2 Hz to 20 kHz. Local Joule heating of the pyroelectric material by a deposited nickel strip is used to achieve fast thermal cycles. Over the whole frequency range, a distinct pyroelectric response is registered. A pyroelectric coefficient of −72 mC/m2K is obtained at a frequency of 10 Hz, which is in good agreement with earlier low-frequency measurements. The pyroelectric current is evaluated with respect to electric field cycling, where a successive increase is observed during wake-up. By comparing measurement results in the low- and high-frequency limit, primary and secondary pyroelectric coefficients of −53 mC/m2K and −19 mC/m2K are estimated, respectively. Si-doped HfO2 is a promising material for future energy harvesting and IR sensor applications due to environmental friendliness and CMOS compatible manufacturing.