1.142 μm GaAsBi/GaAs Quantum Well Lasers Grown by Molecular Beam Epitaxy Xiaoyan Wu, †,‡,∥ Wenwu Pan, †,‡ Zhenpu Zhang, †,§ Yaoyao Li,* ,† Chunfang Cao, † Juanjuan Liu, †,‡ Liyao Zhang, † Yuxin Song, † Haiyan Ou, ∥ and Shumin Wang* ,†,§,⊥ † State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, CAS, Shanghai 200050, China ‡ University of Chinese Academy of Sciences, Beijing 100049, China § ShanghaiTech University, Shanghai 201210, China ∥ Department of Photonics Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark ⊥ Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Gothenburg, Sweden ABSTRACT: As a promising new class of near-infrared light emitters, GaAsBi laser diodes (LDs) are considered to have a high energy efficiency and an insensitive temperature depend- ence of the band gap. In this paper, we realize the longest ever reported lasing wavelength up to 1.142 μm at room temperature in GaAsBi 0.058 /GaAs quantum well LDs grown by molecular beam epitaxy. The output power is up to 127 mW at 300 K under pulsed mode. We also demonstrate continuous wave mode operation up to 273 K for the first time. The temperature coefficient of the GaAsBi/GaAs LD is 0.26 nm/K in the temperature range of 77−350 K, lower than that of both InGaAsP/InP and InGaAs/GaAs LDs. The characteristic temperature is extracted to be 139 K in the temperature range of 77−225 K and decreases to 79 K at 225−350 K. KEYWORDS: GaAsBi, molecular beam epitaxy, laser diodes, quantum well, uncooled laser C urrently InP-based laser diodes (LDs) are widely used in wavelength division multiplexing (WDM) optical com- munication systems, despite the limitations of the low characteristic temperature (T 0 = 60 K) and the wavelength fluctuation depending on the ambient temperature. Thus, thermoelectric coolers are required in practical use, which leads to increasing cost. Therefore, uncooled LDs that can perform very well in energy saving are highly appealing for cost-effective communication systems. Among different approaches including dilute nitride quantum wells (QWs), 1,2 InAs quantum dots (QDs), 3 and dilute bismide QWs, lasers based on GaAsBi are attracting increasing interest due to the suppressed Auger recombination, 4,5 intervalence band absorption (IVBA), 6−9 and temperature-insensitive band gap. 10−14 These significant properties make GaAsBi LDs a promising candidate for energy-efficient near-infrared devices in datacom/telecom systems. 15−17 The GaAs-based dilute nitride QW LDs tend to suffer from large defect-related recombination in addition to Auger recombination. 18 The InAs QD LDs have similarly shown to suffer from Auger recombination and have no significant improvement of temperature stability compared to conventional QW LDs unless p-doping is employed. 19 For dilute bismides, as reported before, the incorporation of Bi can strongly reduce the band gap (E g ) and increase the spin−orbit splitting energy (Δ SO ). 7,8 In practical terms, the Auger recombination and IVBA can be significantly suppressed when the Δ SO is larger than E g . 8 In GaAsBi alloys, the Δ SO > E g band structure is present when the Bi composition is bigger than 10%, where the alloy band gap is close to 1.55 μm. 8 This is significant for the development of highly efficient and uncooled GaAs-based lasers in optical communication systems. 11,20−22 It is well known that the crystal quality of III−V semiconductors is highly affected by the growth temperature. Due to the metastable nature of GaAsBi, a low growth temperature is required compared to that for epitaxial growth of typical (Al)GaAs alloys. 23−26 This leads to an increase in defect density and optical quality degradation. Thus, the main challenge to achieve a GaAsBi LD in the range of 1.3−1.6 μm is the relatively high Bi composition (>10%) with good material quality as required for laser structures. To push the GaAsBi LD wavelength to the telecom wavelength range of 1.3−1.6 μm, a concerted effort to develop high-quality GaAsBi LDs has been made. The first electrically pumped GaAsBi laser was demonstrated by Ludewig et al. in 2013 grown by metal−organic vapor phase epitaxy (MOVPE) (containing 2.2% Bi), lasing at room temperature (RT) (∼947 nm). 27 Then, the first molecular beam epitaxy (MBE)-grown electrically pumped GaAsBi laser was demonstrated by Fuyuki et al. in 2014 with Bi up to 4% (∼1.045 μm at RT). 10 The Received: March 10, 2017 Published: June 5, 2017 Letter pubs.acs.org/journal/apchd5 © XXXX American Chemical Society A DOI: 10.1021/acsphotonics.7b00240 ACS Photonics XXXX, XXX, XXX−XXX