Well, that topic is a little more complex than thatpierre-laurent said:
I would agree with you that "people of Taiwan" (at least the majority of us) are of the Han ethnic group and not "Chinese" (as in citizens of PEOPLE's Republic of China). However, as both of us know, there are still many people out there who are ignorant of the difference between being ethnic Han, citizen of PRC and citizen of ROC/Taiwan and they just lump all of us together as simply, "Chinese", which TECHNICALLY not incorrect because when they use the term "Chinese", they ARE referring to the Han ethnic group, not necessarily citizen of PRC or ROC/Taiwan, or even citizens of HK and Macau.
But in any case, even as polls have shown, not ALL Taiwanese ONLY refer themselves as "Taiwanese", some refer themselves as BOTH Taiwanese AND Chinese while a few ONLY refer themselves as Chinese.