The present disclosure relates to a method for measuring thermal electric characteristics of a semiconductor device, including the steps of: providing at least one current to the LED device over a time interval; recording a voltage transient response of the LED device, wherein the voltage transient response has a plurality of time segments different in gradient; computing a voltage difference from one of the plurality of time segments in the voltage transient response; and determining whether the LED device is defective based on the voltage difference, wherein the voltage difference is thermal dependent. The present disclosure also provides a testing method for defining a plurality of time segments.
