Gain saturation and carrier distribution effects in molecular beam epitaxy grown GaAsSb∕GaAs quantum well lasers

Abstract

Articles you may be interested inGaAs-based room-temperature continuous-wave 1.59 μ m GaInNAsSb single-quantum-well laser diode grown by molecular-beam epitaxy Appl. Phys. Lett. 87, 231121 (2005) GaAsSb/ GaAs quantum well ͑QW͒ lasers grown by solid source molecular beam epitaxy are fabricated into ridge lasers and tested. These devices have a lasing wavelength around 1.2 m that is substantially blueshifted relative to the electroluminescence peak. The magnitude of the blueshift increases as the cavity length is shortened, indicating that the blueshift increases with injection level. This blueshift is attributed to material gain saturation and band filling effects. The internal quantum efficiency is ϳ75%, the transparency current density is ϳ120 A / cm 2 , and the threshold characteristic temperature is ϳ60 K, all typical for GaAsSb/ GaAs based edge emitting lasers. The extracted gain constant is ϳ800 cm −1 for single QW active regions and approximately half that amount for double QWs. This discrepancy is attributed to nonuniform carrier distribution in double QW structures.

High performance GaAsSb∕GaAs quantum well lasers

“…14 As a result, high internal quantum efficiency edge-emitting lasers ͑EELs͒ and high power VCSELs have been demonstrated using this active region structure. 8,11,12,16 Realizing GaAsSb/ GaAs based VCSELs can be challenging because a nearly flat conduction band alignment between GaAs and GaAsSb results in the weak confinement of electrons and the strong confinement of holes and a less than ideal electron-hole wave function overlap that limits gain. 15,17 Furthermore, the combination of limited gain and in-plane composition fluctuations bring about a significant blueshift in the gain peak under injection.…”

“…Temperature dependent threshold current measurements between 0 and 85°C exhibit a characteristic temperature of 60 K, which is close to previous reported results for this material system. [5][6][7]10,12,16 Further temperature dependent device characterization work for this material system is reported in Ref. 16.…”

“…[5][6][7]10,12,16 Further temperature dependent device characterization work for this material system is reported in Ref. 16.…”

“…15,17 Furthermore, the combination of limited gain and in-plane composition fluctuations bring about a significant blueshift in the gain peak under injection. 16 This is an important design concern, as the key to good VCSEL performance is the excellent alignment of the gain peak and the cavity mode at the operating temperature. In designing a VCSEL, it is convenient to establish this alignment based on a wavelength difference between the room temperature active region photoluminescence ͑PL͒ peak and the cavity mode.…”

Improved performance of GaAsSb/GaAs SQW lasers

“…Secondly, due to the lack of lattice matching and high refractive index contrast materials to form all-epitaxial distributed Bragg reflectors (DBRs), it is also very difficult to fabricate monolithic VCSELs in the InP material system [2]. On the other hand, GaAs permits the growth of near lattice-matched GaAs/AlGaAs DBRs, which have superior optical and thermal properties when compared to other III-V DBRs [3]. Furthermore, the fabrication of GaAs based 1.3 µm VCSELs can take full advantage of the industrial standard 850 nm VCSEL fabrication technology, which is attractive from a manufacturing point of view.…”