Crystallographically Aligned 1.508 eV Nitrogen Pairs in Ultra-Dilute GaAs:N: Article No. 090302

We measure polarized photoluminescence emitted from excitons bound to the 1.508 eV N-N impurity pairs in the ultra-dilute semiconductor alloy GaAs:N grown by both metalorganic chemical vapor deposition (MOCVD) and MBE. In MOCVD-grown GaAs:N, the pair orientation is random, with pairs equally distributed over the two equivalent directions in the growth plane. In contrast, MBE results in a highly uniform ensemble of in-plane pairs preferentially aligned in a single <110> direction, and the population of out-of-plane pairs reduced. The results are important for quantum control of N pair qubits where observable energy levels depend on pair orientation.