High performance GaAsSb∕GaAs quantum well lasers

Abstract

Nitrogen incorporation and optical studies of Ga As Sb N ∕ Ga As single quantum well heterostructures J. Appl. Phys. 102, 053106 (2007) GaAsSb/ GaAs quantum wells ͑QWs͒ with 1.3 m light emission are grown using solid-source molecular beam epitaxy. The growth temperature is optimized based on photoluminescence ͑PL͒ linewidth and intensity and edge-emitting laser ͑EEL͒ threshold current density; these measurements concur that the optimal growth temperature is ϳ490°C ͑ϳ500°C͒ for GaAsSb/ GaAs QWs grown with ͑without͒ GaAsP strain compensation. High performance EELs and vertical-cavity surface-emitting lasers ͑VCSELs͒ are demonstrated using the GaAsSb/ GaAs/ GaAsP strain compensated active region. One EEL achieved an output power up to 0.9 W with thresholds as low as 356 A / cm 2 under room temperature pulsed operation, while another achieved continuous-wave ͑cw͒ operation at temperatures up to 48°C for wavelengths as long as 1260 nm. A set of VCSELs achieved room temperature cw operation with output powers from 0.03 to 0.2 mW and lasing wavelengths from 1240 to 1290 nm. The temperature characteristics of these devices indicate that the optimal gain-peak cavity-mode tuning for pulsed operation specifies a room temperature PL peak redshift of 20-30 nm relative to the cavity mode.

Cavity mode gain alignment in GaAsSb-based near-infrared vertical cavity lasers studied by spectroscopy and device measurements

“…Therefore, additional GaAsP layers were introduced, which have a smaller lattice constant than GaAs and partly compensate the strain. [7][8][9][10][11][12] This enables one to grow multiple GaAsSb QWs thereby increasing the luminescence intensity.…”

Role of growth temperature on the physical characteristics of GaAsSb/GaAs QW lasers

“…The devices in this study consist of a triple GaAs 0.9 P 0.1 /GaAs/GaAs 0.7 Sb 0.3 /GaAs/GaAs 0.9 P 0.1 (9nm/5nm/7nm/ 5nm/9nm) strain compensated QW active region grown at 495 0 C (sample B770) and 490 0 C (sample B773). Further details on the optimization of growth temperature and details device growth can be found in [4,5]. Figure 1: Normalised (at T=60K) temperature dependence of the threshold current density, J th (full squares and circles).…”

The influence of growth conditions on carrier recombination mechanisms in 1.3 μm GaAsSb/GaAs quantum well lasers

“…The GaAs 0.9 P 0.1 strain compensating layers allows growing the maximum number of highly strained QWs and reduces strain driven in-plane Sb segregation. 8 The active region in each device is sandwiched between two 20 nm Al 0.25 Ga 0.75 As layers, two 150 nm graded-index AlGaAs layers, one 2 lm n-type Al 0.65 Ga 0.35 As cladding layer followed by 500 nm GaAs buffer layer at the bottom, and one 2 lm p-type Al 0.65 Ga 0.35 As cladding layer followed by a 100 nm GaAs cap layer at the top. The broad-area edge-emitting lasers were processed by defining 50 and 100 lm wide ridges.…”

“…GaAsSb/GaAs lasers may offer a solution in the search for an uncooled, thermally stable and cheaper semiconductor lasers for 1.3 lm OFCS. 7,8 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. 9,10 Furthermore, the fabrication of GaAs based 1.3 lm VCSELs can take full advantage of the industrial standard 850 nm VCSEL fabrication technology, which is attractive from a manufacturing point of view.…”

“…A photoluminescence study of GaAs 0.7 Sb 0.3 /GaAs QW lasers (similar to devices A and B) suggests that antimony segregation causes lower photoluminescence intensity and a larger full-width at half maximum and hence a higher J th . 8 Antimony segregation introduces defects at the GaAsSb active region-GaAs spacer interface forming a thermally activated loss mechanism as more energetic carriers increasingly recombine via the defect states. It follows that the lower growth temperature of device B reduces Sb segregation and the associated defect density and consequently reduces the thermally activated non-radiative processes, thereby reducing J th for device B.…”