The application of laser beam based techniques for ESD defect localization in silicon and gallium arsenide integrated circuits is studied. The Thermal Laser Stimulation technique (OBIRCH, TIVA) is shown to precisely localize electrostatic discharge (ESD) defects under low voltage and current consumption, thus avoiding device or defect degradation upon testing. It is also shown that nonbiased Thermal Laser Stimulation (SEI) tests can localize ESD defects in the silicon substrate. Physical analysis revealed that a thermocouple composed of molten silicon with crystalline silicon generated a Seebeck voltage sufficiently large to be detected. Finally, the pulsed Optical Beam Induced Current technique (OBIC) under no bias condition was evaluated and compared to both biased and nonbiased Thermal Laser Stimulation techniques. It proved to be complementary as it offers a different insight into the ESD induced degradation.