Influence of Bi surfactant on tetrahedral N interstitial formation and optoelectronic properties of dilute GaAsN alloys

Dilute nitride semiconductor alloys are attractive for near- to mid-IR optoelectronic applications but their widespread implementation is hindered by efficiency-limiting non-substitutional N incorporation. Although epitaxy in the presence of surfactants has been reported to increase photoluminescence (PL) emission intensity, the impact of surfactants on N incorporation mechanisms and the resulting optoelectronic properties remains unknown. In this work, we examine the influence of a Bi surfactant on non-substitutional N incorporation and the optoelectronic properties of dilute GaAs_1−x N_x alloy films. For GaAs_1−x N_x alloy films grown with a Bi surfactant, tetrahedral N interstitial (N_tetra) formation is suppressed while the near-band edge PL emission intensity is increased, deep-level PL emission intensity is decreased, and broadening of the photoreflectance resonance is reduced. We discuss the role of the Bi surfactant-induced surface reconstruction transformation on the suppression of N_tetra incorporation, as well as its impact on key optoelectronic properties that are applicable to a variety of highly mismatched alloys.