The role of extended and point defects, and key impurities such as C, O, and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation, and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes, and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.

Gan : processing, defects, and devices

Room-temperature lasing at the wavelength of 1.31 μm is achieved from the ground state of an InGaAs/GaAs quantum-dot ensemble. At 79 K, a very low threshold current density of 11.5 A/cm2 is obtained at a wavelength of 1.23 μm. The room-temperature lasing at 1.31 μm is obtained with a threshold current density of 270 A/cm2 using high-reflectivity facet coatings. The temperature-dependent threshold with and without high-reflectivity end mirrors is studied, and ground-state lasing is obtained up to the highest temperature investigated of 324 K.

1.3 μm room-temperature GaAs-based quantum-dot laser

The surface-emitting laser (SEL) is considered one of the most important devices for optical interconnects and LANs, enabling ultra parallel information transmission in lightwave and computer systems. We introduce its history, fabrication technology, and discuss the advantages. Then, we review the progress of the surface emitting laser and the vertical-cavity surface-emitting laser (VCSEL), covering the spectral band from infrared to ultraviolet by featuring its physics, materials, fabrication technology, and performances, such as threshold, output powers, polarizations, line-width, modulation, reliability, and so on.

Surface-emitting laser-its birth and generation of new optoelectronics field

The design, growth by metal-organic chemical vapor deposition, and processing of an In{sub 0.07}Ga{sub 0.93}As{sub 0.98}N{sub 0.02} solar Al, with 1.0 ev bandgap, lattice matched to GaAs is described. The hole diffusion length in annealed, n-type InGaAsN is 0.6-0.8 pm, and solar cell internal quantum efficiencies > 70% arc obwined. Optical studies indicate that defects or impurities, from InGAsN doping and nitrogen incorporation, limit solar cell performance.

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InGaAsN solar cells with 1.0 eV band gap, lattice matched to GaAs

GaInNAs was proposed and created in 1995 by the authors. It can be grown pseudomorphically on a GaAs substrate and is a light-emitting material having a bandgap energy suitable for long-wavelength laser diodes (1.3-1.55 /spl mu/m and longer wavelengths). By combining GaInNAs with GaAs or other wide-gap materials that can be grown on a GaAs substrate, a type-I band lineup is achieved and, thus, very deep quantum wells can be fabricated, especially in the conduction band. Since the electron overflow from the wells to the barrier layers at high temperatures can he suppressed, the novel material of GaInNAs is very attractive to overcome the poor temperature characteristics of conventional long-wavelength laser diodes used for optical fiber communication systems. GaInNAs with excellent crystallinity was grown by gas-source molecular beam epitaxy in which a nitrogen radical was used as the nitrogen source. GaInNAs was applied in both edge-emitting and vertical-cavity surface-emitting lasers (VCSELs) in the long-wavelength range. In edge-emitting laser diodes, operation under room temperature continuous-wave (CW) conditions with record high temperature performance (T/sub 0/=126 K) was achieved. The optical and physical parameters, such as quantum efficiency and gain constant, are also systematically investigated to confirm the applicability of GaInNAs to laser diodes for optical fiber communications. In a VCSEL, successful lasing action was obtained under room-temperature (RT) CW conditions by photopumping with a low threshold pump intensity and a lasing wavelength of 1.22 /spl mu/m.

GaInNAs: a novel material for long-wavelength semiconductor lasers

A 1.3-/spl mu/m continuous wave lasing operation is demonstrated, for the first time, in a GaInNAs quantum-well laser at room temperature. This lasing performance is achieved by increasing the nitrogen content (up to 1%) in GaInNAs quantum layer. It is thus confirmed that this type of laser is suitable for use as a light source for optical fiber communications.

1.3-μm continuous-wave lasing operation in GaInNAs quantum-well lasers

Vertical-cavity surface-emitting laser diodes with GaInNAs-GaAs quantum-well (QW) active layers are demonstrated for the first time. GaInNAs permits the realization of a long-wavelength vertical-cavity laser grown directly on a GaAs substrate. Room-temperature (RT) pulsed operation is achieved, with an active wavelength near 1.18 /spl mu/m, threshold current density of 3.1 kA/cm/sup 2/, slope efficiency of /spl sim/0.04 W/A, and output power above 5 mW for 45-/spl mu/m-diameter devices. Laser oscillation is observed for temperatures at high as 95/spl deg/C.

GaInNAs-GaAs long-wavelength vertical-cavity surface-emitting laser diodes

Gas-source MBE of GaInNAs for long-wavelength laser diodes

Photopumped operation of a vertical-cavity surface-emitting laser using a single GaInNAs/GaAs quantum well active layer is demonstrated for the first time. The device lases at continuous wave at room temperature, with an active wavelength of 1.22 /spl mu/m and a threshold pump intensity of 3-5 kW/cm/sup 2/, for an equivalent current density of 2-3 kA/cm/sup 2/.

M.C. Larson

Papers

GaInNAs: a novel material for long-wavelength semiconductor lasers

1.3-μm continuous-wave lasing operation in GaInNAs quantum-well lasers

GaInNAs-GaAs long-wavelength vertical-cavity surface-emitting laser diodes

Gas-source MBE of GaInNAs for long-wavelength laser diodes

Room temperature continuous-wave photopumped operation of 1.22 [micro sign]m GaInNAs/GaAs single quantum well vertical-cavity surface-emitting laser