Visible light communications using a Gallium-nitride (GaN) laser diode is reported. Devices, which are cased in TO packages, show modulation bandwidths of up to 1.4 GHz. We demonstrate error-free data transmission, defined as transmission of 1×10(-9) bits without any errors, at 2.5 Gbit/s with a sensitivity of 11.5 dBm.

The low-temperature breakdown of the electroluminescence intensity (ELI) of blue/violet InGaN-based light-emitting diodes (LEDs) is shown to be independent of the structural details of the LED active region. Instead, the presence of an electron blocking layer (EBL) plays a decisive role. The authors attribute the ELI collapse to the low-temperature hole-blocking properties of the EBL. However, removing the EBL leads to a much reduced ELI because of a disproportional increase of electron overflow processes, which shows that the presence of an EBL in blue/violet InGaN-based LEDs is still essential. Optimization of the EBL by means of Mg doping is discussed.

The growth of N-polar (In,Ga)N structures by plasma-assisted molecular beam epitaxy is studied. (In,Ga)N multiple quantum well samples with atomically smooth surface were grown and their good structural quality was confirmed by x-ray diffraction, scanning transmission electron microscopy, and defect selective etching. The In incorporation was higher in the N-polar than in the Ga-polar oriented crystal, consistent with previous reports. However, despite the good morphological and structural properties of these samples, no photoluminescence signal from the (In,Ga)N wells was detected. In contrast, a thick N-polar (In,Ga)N layer exhibited a broad peak at 620 nm in good agreement with the In content determined by x-ray diffraction. The potential source of the luminescence quenching in the N-polar (In,Ga)N multiple quantum wells is discussed and attributed either to a strong nonradiative recombination channel at the surface promoted by the electric field or to the high concentration of point defects at the interfaces of the quantum well structures.

Articles you may be interested inComparative study of polar and semipolar ( 11 2 ¯ 2 ) InGaN layers grown by metalorganic vapour phase epitaxy

We have fabricated two types of InGaN superluminescent diodes applying two different concepts of cavity suppression: a tilted waveguide geometry and passive absorber solution. Both types of devices showed superluminescence behavior, but both eventually lased under the application of high enough current. The lasing threshold turned out to be higher for tilted waveguide devices. By using long (2 mm) waveguides, we managed to demonstrate the power in superluminescent mode exceeding 100 mW in blue/violet part of the spectrum.