Electrical leakage can be either the cause or the effect of circuit failures. Existing detection tools that rely on heat (liquid crystal and fluorescent microthermal imaging) or near-infra-red radiation (thermal imager and emission microscope) associated with the leakage can be fairly effective provided that the ‘hot spot’ is not blocked by metal and, more importantly, the level of leakage is high enough to generate the heat or radiation above certain detection threshold. Using a unique property created by the knock-in implantation of oxygen, we introduce a novel technique that can be used to identify localized leakage at previously unattainable low levels.