Features of the Nonlinear Harmonic Distortion in AOSTFTs

In this article, we present the analysis of the nonlinear harmonic distortion (HD) characteristics for two kinds of amorphous oxide semiconductor thin film transistors (AOSTFTs) based on SiO
₂
/indium-gallium-zinc oxide (IGZO) and HfO
₂
/hafnium-indium-zinc oxide (HIZO), applying the integral function method (IFM). An analysis of the distortion of the transistors used as quasi-linear resistor and the variation in HD as a function of the parameter g
_m
/I
_DS
are also included. As far as we know, this kind of study has not been reported before. It is shown that parameter HD2 does not present a minimum as in MOSFETs, because the transfer characteristic does not present an inflection point. The value of HD2 is higher than that of HD3 in the whole operating ranges. When the transistor is used as quasi-linear resistor for different V
_G
bias, HD2 is greater than HD3 in more than 50 dB. Because HD2 is significantly greater than HD3, the total HD (THD) parameter can be considered practically equal to HD2. In addition, the behavior of HD around the low-power operating region is shown.