The first 108MP images sensor, the Samsung Bright HMX, was used by Xiaomi (that's what the "X" after "HM" stands for). Now Samsung has its own 108MP flagship and those use the HM1 sensor instead, which features some substantial changes. The large 1/1.33" sensor found inside the Samsung Galaxy S20 Ultra uses Nonacell technology, the followup to 2017's Tetracell. Don't worry if you slept through Latin and Greek, these basically mean 9-cell and 4-cell and are Samsung's trademarks for different Bayer filters. Nonacell merges 9 neighboring pixels (from a 3x3 square) into one large 2.4µm...
Source: https://www.gsmarena.com/galaxy_s20_ultras_108mp_sensor_captures_twice_as_much_light_by_grouping_3x3_pixels-news-41501.php
