Design, growth and performance of different QW structures for improved 1300 nm InGaAsP lasers

• Published in: Journal of crystal growth 1998-12, Vol.195 (1), p.700-705
• Main Authors: Silfvenius, Christofer, Landgren, Gunnar
• Format: Article
• Language: English
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Laser materials; Lasers; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Optical materials; Optics; Physics; Semiconductor lasers; laser diodes; Vapor phase epitaxy; growth from vapor phase
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/S0022-0248(98)00565-X

We have investigated the material quality of three alternative InGaAsP 1.3 μm wavelength multiple quantum well structures with strained wells, fabricated by low pressure metal organic vapour phase epitaxy. The designs have radically different compositions but similar calculated properties concerning gain, carrier distribution, laser threshold and optical output power. The structures considered all employ compressively strained wells and have constant-As, constant-Ga or InAsP–InGaAsP materials in wells and barriers. Growth conditions were optimised for each design. Evaluation of the constant-As multiple quantum well (MQW) resulted in poor X-ray diffraction (XRD) and photoluminescence (PL) response. The InAsP MQW exhibited clearly defined XRD-satellites but as the As-content was increased to reach 1.3 μm, PL properties degraded severely. The constant-Ga MQW indicated superior material quality with excellent PL and XRD properties. Fabricated lasers with up to 12 periods and lattice matched barriers, showed internal efficiency values above 95%, internal losses below 10 cm −1, threshold densities as low as 60 A cm −2/well and temperature constant, T 0, values as high as 79 K in the temperature range 20–80°C. The constant-Ga structure allows a variable barrier height, strain compensation and simultaneously avoids the problem with growth undulation and interdiffusion, typically encountered for the InAsP and constant-As cases and should therefore be an excellent candidate for active layers in 1.3 μm lasers.