Enhancement of photoluminescence of GaAsBi quantum wells by parabolic design of AlGaAs barriers

Abstract

Influence of barrier material and structure on carrier quantum confinement in GaAsBi quantum wells (QWs) is studied comprehensively. Single- and multi-QW structures were grown using solid-state molecular beam epitaxy with conventional rectangular, step-like and parabolically graded AlGaAs barrier designs. It was discovered that room temperature photoluminescence is increased by more than 50 times in the GaAsBi QWs with parabolically graded barriers (PGBs) if compared to standard rectangular and step-like structures. The enhancement of photoluminescence was reproducible within the range of growth parameters. The carrier localization and increase of trapping efficiency in GaAsBi QWs is responsible for observed enhancement in radiative properties of PGB structures. The random potential field fluctuations for carriers were increased up to 44 meV due to the blurred well-barrier interface causing the conditions for Bi content and/or well width variations. Due to the impact of self-organizing effects on the reproducibility of optical properties, the GaAsBi QWs with AlGaAs PGBs open the window for fabrication of 1.0–1.55 μm wavelength emission lasers based on GaAsBi quantum structures.

Photoluminescence properties of GaAsBi single quantum wells with 10% of Bi

“…It has been already demonstrated that GaAsBi multiple quantum wells (MQW) with 10% of Bi exhibit room temperature photoluminescence at the wavelengths as long as 1.43 μm [4]. A proper design of the structures can enable enhancement of the luminescence up to a factor of 50 [5]. A complex study revealed that the technological parameters of molecular beam epitaxy (MBE) growth such as Bi flux and the group III to V pressure ratio play an essential role in obtaining high quality bismide quantum well (QW) structures and that appropriate conditions allow one to introduce a larger content of Bi while still keeping pseudomorphic compressively strained QWs.…”

Low-Frequency Noise Characteristics of (Al, Ga)As and Ga(As, Bi) Quantum Well Structures for NIR Laser Diodes

“…Although their technology is well developed, applications of the GaAs- and (Al, Ga)As-based LDs are held back by losses caused by the Auger non-radiative recombination and temperature-sensitivity of the radiation wavelength. In our previous works, the advantages of the introduction of Bi into the GaAs lattice by substituting As for optoelectronic devices were demonstrated [ 7 , 8 ]. It is well known that Bi presence modifies the GaAs bandgap leading to the partial suppression of the non-radiative Auger recombination: with incorporation of Bi atoms into the GaAs lattice, the valence band is mainly modified, while the change in the conducting band is significantly weaker.…”

“…However, such atypical epitaxy conditions weaken the radiative recombination process and affect the optical properties of the structure. Therefore, attempts to fabricate (Al, Ga)As-based laser diodes with similar characteristics as LDs based on Ga(As, Bi) QWs varying the quantity of Al (from pure GaAs to (Al, Ga)As with up to 10%Al) in the QWs and the profile of the barriers have been carried out [ 7 ]. Experimental investigation and modeling of optoelectronic devices with parabolic (and other non-rectangular) quantum structures are quite often shown in the scientific literature [ 7 , 11 , 12 , 13 , 14 , 15 , 16 ].…”

“…Therefore, attempts to fabricate (Al, Ga)As-based laser diodes with similar characteristics as LDs based on Ga(As, Bi) QWs varying the quantity of Al (from pure GaAs to (Al, Ga)As with up to 10%Al) in the QWs and the profile of the barriers have been carried out [ 7 ]. Experimental investigation and modeling of optoelectronic devices with parabolic (and other non-rectangular) quantum structures are quite often shown in the scientific literature [ 7 , 11 , 12 , 13 , 14 , 15 , 16 ]. Enhancement of the photoluminescence (increase in the radiating transition probability and efficiency) in structures with parabolic QWs (PQWs) in comparison with the rectangular ones is demonstrated: grading of the barrier layer doping pulls electron and hole wave functions into a narrow region, which reduces their spatial separation in the QW [ 13 , 14 , 15 ].…”

“…This effect is related to the increased carrier trapping efficiency and pronounced localization effect in the GaAsBi PQWs [ 14 , 15 ]. The carrier localization and increase in the trapping efficiency in the GaAsBi QWs is responsible for the observed enhancement in the radiative properties of the parabolically graded barriers’ (PGBs’) structures [ 7 , 17 ]. Therefore, radiating devices with PQWs are more efficient than those with conventional rectangular QWs [ 13 , 14 ].…”