Μm Photoluminescence Emission Research Articles

1.5 μm photoluminescence and upconversion photoluminescence in GeGaAsS:Er chalcogenide glass

Abstract The paper reports on ≈1.5 μm Stokes photoluminescence (PL) emission and upconversion photoluminescence (UCPL) emission in the visible and near-infrared spectral region in Er3+-doped Ge25Ga8As2S65 chalcogenide glasses at pumping wavelengths of 980 and 1550 nm. The ≈1.5 μm PL emission spectra are broadened with increasing concentration of Er ions which is discussed in terms of radiation trapping and UCPL dynamics affecting the Er3+: 4 I 13/2 level lifetime. The UCPL emission was observed at ≈530, ≈550, ≈660, ≈810 and ≈990 nm and its overall intensity as well as red-to-green UCPL emission intensity ratio increases with increasing Er concentration. To explore the UCPL dynamics we measured double logarithmic dependency of green (≈550 nm) and red (≈660 nm) UCPL emission versus pump power at pumping wavelength of 975 nm. Moreover, we measured quadrature frequency resolved spectroscopy (QFRS) on green UCPL emission (≈550 nm) using 975 nm pumping wavelength and various excitation powers. The QFRS spectra on green UCPL were analyzed in term of QFRS transfer function for three-level model from which we deduced energy transfer upconversion rate w 11 (s−1) originating from Er3+: 4 I 11/2, 4 I 11/2→4 F 7/2, 4 I 15/2 transitions.

GaAsBi/GaAs MQWs grown by MBE using a two-substrate-temperature technique

Eleven periods of GaAsBi/GaAs multiple quantum wells (MQWs) on (100) GaAs substrates were grown by molecular beam epitaxy (MBE) using the two-substrate-temperatures (TST) technique. In the TST technique, the substrate temperature was set at TGaAsBi = 350 °C for GaAsBi layers and TGaAs = 550 °C for GaAs layers for the growth of MQWs. The structural and optical characterization of GaAsBi/GaAs MQWs using TST technique was carried out for growth optimization by changing As4/Ga beam equivalent pressure (BEP) ratio. Atomic force microscope observation shows high As4/Ga BEP ratio supply can prevents roughening of the GaAsBi layer surface of MQWs. High resolution x-ray diffraction analysis results reveal Bi incorporation enhancement with increasing As4/Ga BEP ratio. The reciprocal space mapping shows highly strained MQWs layers can be grown without relaxation with respect to the GaAs substrate at optimized growth conditions. At room temperature 1.22 μm photoluminescence emission was obtained from GaAs0.962Bi0.038/GaAs MQWs grown using TST technique.

Erbium-doped a-plane GaN epilayers synthesized by metal-organic chemical vapor deposition

A-plane GaN epilayers doped with erbium (GaN:Er) have been grown on r-plane sapphire substrates by metal organic chemical vapor deposition. The 1.54 µm emission properties were probed by photoluminescence (PL) emission spectroscopy and compared with those of c-plane GaN:Er. It was found that the emission intensity from a-plane GaN:Er is 4 times higher than that of c-plane GaN:Er. The intensity of the 1.54 µm emission was found to increase with increasing Er molar flux. A-plane Er-doped GaN epilayers exhibit a small thermal quenching effect, with only a 12% decrease in the integrated intensity of the 1.54 µm PL emission, occurred between 10 and 300 K.

Photoluminescence investigation of erbium-implanted in KTiOPO4 and RbTiOPO4

KTiOPO4 (KTP) and RbTiOPO4 (RTP) crystals have been implanted with 500keV Er ions at a dose of 3×1015ions/cm2 with the aim of optically doping the material in the near surface region. The sample was annealed at 500°C for 90min in oxygen atmosphere after implantation. Photoluminescence (PL) and Rutherford backscattering spectrometry studies were performed on the as-implanted samples before and after annealing. 1.54μm photoluminescence emission was observed at both room-temperature and low-temperature in KTP without any annealing. After annealing luminescence intensity is improved at 12K and photoluminescence quenching were found at room temperature for both samples. The reasons are discussed in the paper.

Facile synthesis of large scale Er‐doped ZnO flower‐like structures with enhanced 1.54 μm infrared emission

AbstractA new strategy to introduce metallic dopant into ZnO structures by a wet chemical reaction is presented. Single‐crystal Er‐doped ZnO flower‐like structures have been synthesized on ZnO‐coated silicon substrate by a low temperature hydrothermal process. The Er‐doped ZnO structures exhibit promising 1.54 μm photoluminescence emission for optoelectronic communication. The successful doping has been confirmed by the X‐ray diffraction, transmission electron microscopy, X‐ray photoemission spectroscopy and photoluminescence measurements. The achievement to introduce Er dopants into ZnO flower‐like structures by the time‐ and cost‐effective wet chemical reaction at low temperature for the first time has vast potential to scale up for possible applications. The photoluminescence properties are significantly improved compared to that reported in the literature for the Er‐doped nanowires and thin films and shall be much more applicable in optical and communication devices. The flower‐like structures are expected to be advantageous in serving as a multi‐directional infrared emitters and/or detectors. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

1.54 μ m photoluminescence emission and oxygen vacancy as sensitizer in Er-doped HfO2 films

In this letter, we report on the characteristics of 1.54μm photoluminescence emission of Er-doped HfO2 films synthesized by pulsed laser deposition and ion implantation. An efficient emission at 1.54μm in the annealed HfO2 films has been observed under a broad band excitation from 400nm to a higher energy at room temperature. X-ray diffraction and electron paramagnetic resonant measurements were used to analyze the correlation between the optical properties and microstructures. An energy transfer mechanism is proposed that the O vacancy in the bulk acts as an effective sensitizer for the neighboring Er ions and greatly enhances the 1.54μm band emission. These results lay an important basis for the future silicon-based integrated optoelectronic device applications of Er-doped HfO2 films.

Critical parameters for the molecular beam epitaxial growth of 1.55μm (Ga,In)(N,As) multiple quantum wells

The authors discuss the effect of substrate temperature and As beam equivalent pressure (BEP) on the molecular beam epitaxial growth of (Ga,In)(N,As) multiple quantum wells (MQWs). Transmission electron microscopy studies reveal that a low substrate temperature essentially prevents composition modulations. Secondary ion mass spectrometry results indicate that a low As BEP reduces the incorporation competition of group V elements. The low substrate temperature and low As BEP growth condition leads to (Ga,In)(N,As) MQWs containing more than 4% N preserving good structural and optical properties, and hence demonstrating 1.55μm photoluminescence emission at room temperature.

Erbium-doped GaN epilayers synthesized by metal-organic chemical vapor deposition

The authors report on the synthesis of Er-doped GaN epilayers by in situ doping by metal-organic chemical vapor deposition (MOCVD). The optical and electrical properties of the Er-doped GaN epilayers were studied by photoluminescence (PL) spectroscopy and van der Pauw–Hall method. Both above and below band gap excitation results in a sharp PL emission peak at 1.54μm. In contrary to other growth methods, MOCVD grown Er-doped GaN epilayers exhibit virtually no visible emission lines. A small thermal quenching effect, with only a 20% decrease in the integrated intensity of the 1.54μm PL emission, occurred between 10 and 300K. It was found that Er incorporation has very little effect on the electrical conductivity of the GaN epilayers and Er-doped layers retain similar electrical properties as those of undoped GaN.

Long wavelength emitting InAs∕Ga0.85In0.15NxAs1−x quantum dots on GaAs substrate

InAs quantum dots (QDs) overgrown by a Ga0.85In0.15NxAs1−x (0⩽x⩽0.017) layer have been realized on GaAs substrate by molecular beam epitaxy. When the nitrogen composition increases, the photoluminescence (PL) wavelength redshifts up to 1.52μm. It is shown that PL properties of InAs∕Ga0.85In0.15N0.012As0.988 QDs are improved by thermal annealing. Finally, 1.45μm PL emission with a 38.5meV full width at half maximum is obtained at room temperature.

1.3-1.4 µm photoluminescence emission from InAs/GaAsquantum dot multilayer structures grown on GaAs singular andvicinal substrates

Optical and structural properties of multilayerstructures with InAs/GaAs quantum dots are investigated. It isshown that under optimal growth conditions, 1.3-1.4 µmemission can be achieved. Possible scenarios of quantum dotbehaviour evaluation are discussed in a frame of elastic theoryto explain differences in optical properties of the grownstructures.