More than 200 former employees of an RCA television and semiconductor plant in northern Taiwan have died of cancer and at least 1,000 others are suffering from the disease, in what industry watchdogs are calling the worst cancer cluster in the history of high-tech. A group of former plant workers arrived in Silicon Valley yesterday to tell their story and plead for justice, which has to date been elusive. Workers believe that the plant polluted the groundwater with toxic chemicals, leading to stillborn babies and cancer cases, but a 1999 lawsuit filed in Taiwan by former workers was dismissed, and a study conducted by the Taiwanese government showed no correlation between the company facilities and the health problems. After two decades of operation, the plant was shut down in 1991 and declared a toxic site by the Taiwanese Environmental Protection Agency. General Electric, former owner of RCA, and the French company Thomson Multimedia, the current owner, spent millions of dollars to clean up the site, but deny that the plant could have caused health problems. In the Bay Area, the former workers are meeting with environmental groups, AFL-CIO leaders, U.S. Labor Department officials, and members of Congress, and they are contemplating filing suit in the United States.