Han Chinese 漢人/漢族 is the name of the ethnic group which originated from mainland China, and are the most dominant in mainland China, Hong Kong, Macau, and Taiwan.
OP here is probably trying to differentiate between Chinese (nationality) and Han Chinese (ethnicity) because although people in Taiwan are of Han Chinese ethnicity, they generally don't like to be called Chinese (nationality) and prefer to be called Taiwanese (nationality, though the official name of the country is Republic of China, but that's another story).