TheA,B,Cluminescence system from silicon is believed to originate with the radiative decay of an exciton bound to an isoelectronic trap. It was shown previously by Sauer, Weber, and Zulehner [Appl. Phys. Lett.44, 440 (1984)] that nitrogen is one of the trap constituents. We present experimental evidence that confirms that aluminum is also a trap constituent, suggesting that the trap is an aluminum‐nitrogen pair.