Optically pumped GaN-AlGaN double-heterostructure lasers grown by ECR-GSMBE and HVPE

Conference · Fri Nov 01 04:00:00 EST 1996

OSTI ID:395048

Maki, P A; Molnar, R J; Aggarwal, R L; Liau, Z L; Melngailis, I ^[1]

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1. Massachusetts Inst. of Tech., Lexington, MA (United States). Lincoln Lab.

The authors have observed laser emission with well-defined cavity modes in optically pumped GaN-Al{sub 0.1}Ga{sub 0.9}N double-heterostructure (DH) lasers. The laser structures were grown using an electron-cyclotron-resonance nitrogen-discharge source and gas-source molecular beam epitaxy (ECR-GSMBE) on thick ({ge} 10 {micro}m) GaN buffers grown by hydride vapor-phase epitaxy (HVPE) on c-plane sapphire. Transversely pumped cavities using a 337.1 nm nitrogen laser pump source exhibit a threshold pump fluence ranging from 0.15 to 0.3 mJ/cm{sup 2} at 77 K, a linear light output above threshold, a lasing wavelength of 358 nm, and an estimated differential quantum efficiency of 1%. The room-temperature threshold is about 1.7 times higher. Longitudinal mode structure has been resolved in a shorter-cavity (23 {micro}m) device at 77 K. The measured mode spacing of 0.56 nm corresponds to a group index of 5.0. Far-field measurements in a plane perpendicular to the plane of the heterostructure indicate a double-lobed pattern for a 1,000 {angstrom} thick GaN active region, and a single lobe with a FWHM of 60{degree} for a 4,000 {angstrom} active region. The thick HVPE GaN buffer layer provides for a lattice-matched growth and results in improved nucleation in MBE, as indicated by a high-quality reflection-electron-diffraction pattern of the as-loaded wafers. The surface morphology of the MBE layers on the HVPE buffer shows improved optical smoothness as compared to layers grown directly on sapphire using a low-temperature, MBE-grown GaN buffer. Laser facets were formed either by saw cutting or cleaving of the GaN buffer and epilayer along crystal planes. Details of the material development and laser performance are described.

• OSTI ID: 395048
• Report Number(s): CONF-951155--; ISBN 1-55899-298-7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
ALUMINIUM NITRIDES
COMPOSITE MATERIALS
ELECTRON CYCLOTRON-RESONANCE
ELECTRON DIFFRACTION
ELECTRON MOBILITY
EMISSION SPECTRA
ENERGY BEAM DEPOSITION
GALLIUM NITRIDES
LASER RADIATION
MOLECULAR BEAM EPITAXY
MORPHOLOGY
PHOTOLUMINESCENCE
SAPPHIRE
SCANNING ELECTRON MICROSCOPY
SEMICONDUCTOR LASERS
SEMICONDUCTOR MATERIALS
VAPOR PHASE EPITAXY