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Abstractauthoren We report the growth of green emitting InGaN quantum wells (QWs) by metal-organic vapor-phase epitaxy (MOVPE) on three-dimensional GaN templates. The [ABSTRACT FROM AUTHOR]

We report on passive mode locking of a semiconductor disk laser emitting pulses shorter than 250 fs at 664 nm with a repetition frequency of 836 MHz. A fast saturable absorber mirror fabricated by metal-organic vapor-phase epitaxy in a near-resonant design was used to enable the mode locking operation. It includes two GaInP quantum wells located close to the surface and an additional fused silica coating. The emission spectrum shows the superposition of a soliton-like part and a smaller 'continuum' part. [ABSTRACT FROM AUTHOR]

We demonstrate an optically pumped semiconductor disk laser (OP-SDL) using InP quantum dots (QDs) as active material fabricated by metal-organic vapor-phase epitaxy. The QDs are grown within [(Al0.1Ga0.9)0.52In0.48]0.5P0.5 (abbr. Al0.1GaInP) barriers in order to achieve an emission wavelength around 655 nm. We present optical investigations of the active region showing typical QD behavior like blue shift with increasing excitation power and single emission lines, which show anti-bunching in an intensity auto-correlation measurement. We report maximum output powers of the OP-SDL of 1.39 W at low emission wavelength of ∼654 nm with a slope efficiency of ηdiff=25.4 %. [ABSTRACT FROM AUTHOR]

Abstract: Quaternary AlInGaN quantum wells in GaN barriers were grown by metal-organic vapor-phase epitaxy. Changing to a growth sequence with pulsed metal-organic supply leads to structures with enhanced photoluminescence efficiencies. The amount of material was varied, resulting in AlInGaN layer thicknesses between nominally 1.5 and 10nm. We have analyzed the material properties by X-ray diffraction (XRD) as well as photoluminescence (PL) spectroscopy. The observed XRD-spectra and the PL intensity show the high quality of the deposited material. By analyzing the PL spectra, we have found an energy shift of the resonance lines from 2.65 to 3.33eV with decreasing well thickness. We attribute this shift mainly to the presence of internal electric fields in the AlInGaN/GaN heterostructures. Power-dependent and time-resolved PL experiments confirm this observation. By properly adjusting the material composition, we could achieve polarization field compensation of the quaternary QW structures. Also, first luminescence experiments on ternary InGaN QW embedded in quaternary barrier material were performed. [Copyright &y& Elsevier]

We have fabricated InGaN nanostructures on top of GaN hexagonal pyramids by selective metalorganic vapor-phase epitaxy. With this approach, we are able to exactly control the position of the emitting quantum dot, which is an essential requirement for functionalized single-photon emitters. The emission properties as well as the relaxation and recombination mechanisms were investigated using spectroscopic methods. Regions of different confinement were identified, with the photoluminescence emission from the InGaN quantum dots around 2.03 eV and a decay time of 1.4 ns. The constant temperature behavior of the radiative decay time confirms its zero-dimensional character. Spatially resolved cathodoluminescence measurements attribute this emission to the apex of the pyramid. [ABSTRACT FROM AUTHOR]

We perform excited-state spectroscopy of single self-assembled lateral InGaAs quantum dot molecules embedded in a planar microcavity structure, which are grown using a combination of metal-organic vapor phase and solid-source molecular beam epitaxy. The individual quantum dot molecules (QDMs) consist of two single dots that are coupled along the [ 1Ï0] crystal direction via electron tunneling. By microphotoluminescence excitation spectroscopy, we investigate the presence and structure of the excited states confined in the system using a wide-band tunable Ti: sapphire laser source. We show that the excited states are very similar even for different molecules. We attribute this to the presence of a potential basin below the quantum dots that levels the differences among various QDMs. [ABSTRACT FROM AUTHOR]

Abstract: Measured power–current curves of 660nm AlGaInP-based oxide-confined vertical-cavity surface-emitting lasers (VCSEL) are compared with calculated data by a cylindrical heat dissipation model to improve heat removal out of the device. Pulsed lasing operation of a 670nm VCSEL at high temperatures is demonstrated. At +120°C heat sink temperature we exceeded 0.5mW and at +160°C still output power were achieved. [Copyright &y& Elsevier]

Abstract: We report the growth and characterisation of AlInGaN by metalorganic vapor phase epitaxy (MOVPE). The thick layers (approx. 50nm) have been grown with various TMAl flows, carrier gases and growth temperature to investigate their influence on the structural and optical properties. Our main interest is the reduction of the built-in electric field related to the strain in the layer. For that reason, high-resolution X-ray diffraction (XRD), Rutherford backscatter spectrometry (RBS) and photoluminescence (PL) enable us to determine the strain state, lattice constant and luminescence energy, depending on the quaternary composition. Quantum wells were also grown in model device structures in order to determine their utility in optoelectronic applications. [Copyright &y& Elsevier]

Abstract: AlInGaN offers many possibilities for optoelectronic applications in the blue and ultraviolet emission range. Since band gap and lattice constant can be adjusted independently, the following reduction of strain and defects in the active layer will enhance some characteristics of nitride laser diodes, like output power or lifetime. For quantum dot structures, ultra-low threshold, high material gain and improved temperature stability have been theoretically predicted. We investigate the growth of AlInGaN and the formation mechanism of quantum dots depending on the main epitaxy parameters like growth temperature, amount of deposited material, TMAl flow or even its carrier gas. At 760C, a narrow distribution of quantum dots was achieved, and depending on the growth conditions, the maximum dot density was about dots/cm and with average heights of 30nm. Photoluminescence measurements of uncapped samples showed narrow emission peaks between 2.7 and 2.95eV. [Copyright &y& Elsevier]

Abstract: In this letter, we report on laser light emission, in the red spectral range, of electrically pumped self-assembled InP quantum dots which were embedded in a microcavity structure realized by monolithically grown highly reflective AlGaAs distributed Bragg reflectors. Common semiconductor laser processing steps were used to fabricate stand-alone index-guided vertical-cavity surface-emitting lasers with oxide apertures for optical transverse mode confinement and electrical current constriction. Ultra-low threshold current densities of around 10A/cm2 and room temperature lasing were achieved. [Copyright &y& Elsevier]