Search

Transfer printing is becoming widely adopted as a back-end process for the hybrid integration of photonic and electronic devices. Integration of membrane components, with micrometer-scale footprints and sub-micron waveguide dimensions, imposes strict performance requirements on the process. In this review, we present an overview of transfer printing for integrated photonics applications, covering materials and fabrication process considerations, methods for efficient optical coupling, and high-accuracy inter-layer alignment. We present state-of-the-art integration demonstrations covering optical sources and detectors, quantum emitters, sensors, and opto-mechanical devices. Finally, we look toward future developments in the technology that will be required for dense multi-materials integration at wafer scales. [ABSTRACT FROM AUTHOR]

An elliptic focusing neutron guide was combined with a cold neutron imaging instrument to produce a cone-beam, whose parameters were then characterized both at the focal point and at the detector position. This point source geometry provides improved experimental conditions for tomographic applications, providing a larger beam cross-section and enabling geometric magnification. The experimental data were compared with Monte Carlo simulations and both experiments and simulations demonstrate superior spectral and geometric homogeneity of the cone-beam setup compared to the conventional pinhole geometry. [ABSTRACT FROM AUTHOR]

We report on the comparative electronic state characteristics of particular GaInNAs/GaAs quantum well structures that emit near 1.3 and 1.5 μm wavelength at room temperature. While the electronic structure of the 1.3 μm sample is consistent with a standard quantum well, the 1.5 μm sample demonstrate quite different characteristics. By using photoluminescence (PL) excitation spectroscopy at various detection wavelengths, we demonstrate that the macroscopic electronic states in the 1.5 μm structures originate from phase-separated quantum dots instead of quantum wells. PL measurements with spectrally selective excitation provide further evidence for the existence of composition-separated phases. The evidence is consistent with phase segregation during the growth leading to two phases, one with high In and N content which accounts for the efficient low energy 1.5 μm emission, and the other one having lower In and N content which contributes metastable states and only emits under excitation in a particular wavelength range. [ABSTRACT FROM AUTHOR]

We report studies of the effect of rapid thermal annealing (RTA) on the optical properties of a low-loss 1.3 μm saturable Bragg reflector (SBR), consisting of a GaInNAs/GaAs single quantum well embedded in an AlAs/GaAs Bragg reflector grown monolithically on a GaAs substrate. RTA gives rise to a blueshift of the photoluminescence (PL) peak (and therefore of the excitonic absorption peak) and an enhancement of PL intensity, while the reflectivity properties including peak reflectivity and bandwidth are not degraded. Temperature dependent photoluminescence measurements show that the RTA-induced blueshift of photoluminescence consists of two components: one originating from the increase of optical transition energies and another from the reduction of carrier localization. Time-resolved photoluminescence results at room temperature provide information about the recombination dynamics of carriers directly relevant to the application of the SBR in laser mode locking. [ABSTRACT FROM AUTHOR]

We report on the characteristics of quantum well intermixing in GaInNAs/GaAs structures of differing N content. Rapid thermal annealing combined with SiO[sub 2] caps deposited on the surface of the samples is used to disorder 1.3 μm GaInNAs/GaAs multiquantum wells which have been preannealed in-situ to the stage of blueshift saturation. The different effects of two capping layer deposition techniques on the interdiffusion of In–Ga have been compared, particular regarding the role of sputtering processes. The dependence of quantum well intermixing-induced photoluminescence blueshift on N concentration has provided extra information on the intrinsic properties of the GaInNAs/GaAs material system. We found that the blueshift decreases as the N concentration increases. This finding not only rules out the possible mechanism of N–As interdiffusion, but also demonstrates the alloy stability of GaInNAs due to the strong bond between In[Single_Bond]N. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Rapid thermal annealing combined with SiO[sub 2] caps deposited on the surface of samples by different techniques is used to selectively disorder 1.3 µm GaInNAs/GaAs multiquantum wells which have been preannealed in situ to the stage of blueshift saturation. After thermal annealing under specific conditions, a shift in band gap of over 170 meV has been obtained in sputtered SiO[sub 2]-capped samples, while uncapped and plasma enhanced chemical vapor deposited SiO[sub 2]-capped samples demonstrated a negligible shift. Quantum well intermixing in sputtered SiO[sub 2]-capped samples originates from enhanced compositional interdiffusion due to the generation of point defects by ion bombardment during the sputtering process. Secondary ion mass spectrometry has confirmed that the enhanced blueshift was caused by the interdiffusion of group III atoms (In and Ga) between the quantum wells and barriers. Detailed photoluminescence and excitation spectroscopy were performed to study the optical properties of both intermixed and nonintermixed samples. [ABSTRACT FROM AUTHOR]

Micro-light emitting diode (LED) arrays with diameters of 4 to 20 μm have been fabricated and were found to be much more efficient light emitters compared to their broad-area counterparts, with up to five times enhancement in optical power densities. The possible mechanisms responsible for the improvement in performance were investigated. Strain relaxation in the microstructures as measured by Raman spectroscopy was not observed, arguing against theories of an increase in internal quantum efficiency due to a reduction of the piezoelectric field put forward by other groups. Optical microscope images show intense light emission at the periphery of the devices, as a result of light scattering off the etched sidewalls. This increases the extraction efficiency relative to broad area devices and boosts the forward optical output. In addition, spectra of the forward emitted light reveal the presence of resonant cavity modes [whispering gallery (WG) modes in particular] which appear to play a role in enhancing the optical output. [ABSTRACT FROM AUTHOR]

The optical properties of GaInNAs/GaAs multi-quantum wells were investigated by photoluminescence excitation (PLE) spectroscopy, as well as by photoluminescence (PL), under various excitation intensities and at various temperatures. The PLE spectra demonstrated pronounced excitonic features and the corresponding transitions were identified. At low temperatures the PL spectra were sensitive to the excitation intensity. Under fixed excitation intensity, both the peak energy and the linewidth of photoluminescence showed anomalous temperature dependence, specifically an S-shaped temperature dependence of the peak energy and a N-shaped temperature dependence of linewidth in the PL spectra. The observed results are explained consistently in terms of the exciton localization effect due to the local fluctuations of nitrogen concentration. [ABSTRACT FROM AUTHOR]

Methods of fabricating negative and bifocal microlens arrays have been demonstrated in this paper. The technique of photoresist molding using a sapphire positive lens template was used for the patterning of negative microlenses, while the bifocal microlens arrays were fabricated using a two-step etch process. In both cases, the lenses were etched using inductively coupled plasma. Microlenses with diameters as small as 10 μm have been demonstrated and were characterized using atomic force microscopy and confocal microscopy. The lens arrays were found to be smooth, uniform, and to have focal lengths consistent with their design and calculated values. [ABSTRACT FROM AUTHOR]

A mechanically flexible and wavelength-tunable laser with an ultra-thin glass membrane as substrate is demonstrated. The optically pumped hybrid device has a distributed feedback cavity that combines a colloidal quantum dot gain film with a grating-patterned polymeric underlayer, all on a 30-µm thick glass sheet. The total thickness of the structure is only 75 µm. The hybrid laser has an average threshold fluence of 450680 µJ/cm² (for 5-ns excitation pulses) at an emitting wavelength of 607 nm. Mechanically bending the thin-glass substrate enables continuous tuning of the laser emission wavelength over an 18-nm range, from 600nm to 618 nm. The correlation between the wavelength tunability and the mechanical properties of the thin laser structure is verified theoretically and experimentally. [ABSTRACT FROM AUTHOR]

The transfer printing of 2 μm-thick aluminum indium gallium nitride (AlInGaN) micron-size light-emitting diodes with 150 nm (±14 nm) minimum spacing is reported. The thin AlInGaN structures were assembled onto mechanically flexible polyethyleneterephthalate/polydimethylsiloxane substrates in a representative 16 × 16 array format using a modified dip-pen nano-patterning system. Devices in the array were positioned using a pre-calculated set of coordinates to demonstrate an automated transfer printing process. Individual printed array elements showed blue emission centered at 486 nm with a forward-directed optical output power up to 80 μW (355 mW/cm2) when operated at a current density of 20 A/cm2. [ABSTRACT FROM AUTHOR]

Periodically nano-patterned organic films incorporating color converting light-emitting polymers have been integrated onto InGaN/GaN light-emitting diodes (LEDs). Polarized and strongly modified hybrid LED emission is observed due to the photonic crystal effect of the nano-pattern. Emission characteristics are appropriate for various applications, and fast modulation capability with an optical -3 dB bandwidth of 168 MHz is demonstrated. [ABSTRACT FROM AUTHOR]

The processing of N-polar GaN [formula] samples has been studied, motivated by applications in which extensive back side thinning of freestanding GaN (FS-GaN) substrates is required. Experiments were conducted on FS-GaN from two commercial sources, in addition to epitaxial GaN with the N-face exposed by a laser lift-off process. The different types of samples produced equivalent results. Surface morphologies were examined over relatively large areas, using scanning electron microscopy and stylus profiling. The main focus of this study was on inductively coupled plasma (ICP) etch processes, employing Cl2/Ar or Cl2/BCl3Ar gas mixtures. Application of a standard etch recipe, optimized for feature etching of Ga-polar GaN (0001) surfaces, caused severe roughening of N-polar samples and confirmed the necessity for specific optimization of etch conditions for N-face material. A series of recipes with a reduced physical (sputter-based) contribution to etching allowed average surface roughness values to be consistently reduced to below 3 nm. Maximum N-face etch rates of 370–390 nm/min have been obtained in recipes examined to date. These are typically faster than etch rates obtained on Ga-face samples under the same conditions and adequate for the process flows of interest. Mechanistic aspects of the ICP etch process and possible factors contributing to residual surface roughness are discussed. This study also included work on chemomechanical polishing (CMP). The optimized CMP process had stock removal rates of ∼500 nm/h on the GaN N face. This was much slower than the ICP etching but showed the important capability of recovering smooth surfaces on samples roughened in previous processing. In one example, a surface roughened by nonoptimized ICP etching was smoothed to give an average surface roughness of ∼2 nm. [ABSTRACT FROM AUTHOR]

We report on the influence of surface-related states on the relaxation of carriers within single (Ga,In)N/GaN quantum wells. Two identical samples that differ only in the thickness of the top GaN cap layer were studied. Photoluminescence and pump-probe measurements reveal significant variations in the quantum well integrated emission and the carrier relaxation decay times in the two samples, when probing both the ground and excited states of the wells. The variations are attributed to the presence of an efficient nonradiative relaxation channel associated with the proximity of the quantum well excitations to the surface-related states in the thin-cap sample. [ABSTRACT FROM AUTHOR]

Comparable microcavities with 3λ/2 (∼240 nm) active regions containing distributed (In,Ga)N quantum wells, grown on GaN substrates and bounded by two dielectric mirrors, have been fabricated by two different routes: one using laser lift-off to process structures grown on GaN-on-sapphire templates and the second using freestanding GaN substrates, which are initially processed by mechanical thinning. Both exploit the properties of an Al0.83In0.17N layer, lattice matched to the GaN substrate and spacer layers. In both cases cavity quality factors >400 are demonstrated by measurements of the cavity-filtered room-temperature excitonic emission near 410 nm. [ABSTRACT FROM AUTHOR]

Light-emitting diodes (LEDs) in the form of a one-dimensional array of microstripes emitting at 370 nm were fabricated from AlInGaN inorganic semiconductor. These microlight sources were then used to “directly write” microstructures in photocurable blends of organic light-emitting polymers (LEPs) spin coated onto the LED surface. In this way, thin microstripes of LEP as narrow as 50 μm have been fabricated and integrated with the micro-LEDs. These “self-aligned” polymer microstripes serve as wavelength downconverters under further excitation by the UV micro-LEDs, producing hybrid inorganic/organic microstructured LEDs. [ABSTRACT FROM AUTHOR]

The authors report the temperature dependent photoluminescence characteristics of a series of GaInNAsSb/Ga(N)As double quantum wells which all emit at 1.5–1.55 μm at room temperature and whose design is such that the quantum wells have nominally identical valence band profiles but show different confinement depth in the conduction band. The photoluminescence quenching at high temperature demonstrates a thermal activation energy independent of the conduction band offset and can be most plausibly attributed to the unipolar thermalization of holes from the quantum wells to the barriers. This effect will intrinsically limit the flexibility of heterostructure design using GaInNAs(Sb), as it would for any other material system with small valence band offset. [ABSTRACT FROM AUTHOR]

We investigate the influence of quantum-well intermixing (QWI) on the electronic band structure of GaInNAs/GaAs multiquantum wells. The band structures and optical transitions have been calculated based on the band-anticrossing (BAC) model and Fick’s interdiffusion law for both intermixed and nonintermixed samples, respectively. The calculated results are consistent with the true optical transitions observed by photoluminescence excitation spectroscopy and secondary ion mass spectroscopy. Our investigation indicates that BAC model is valid for interdiffused quantum wells and verifies that the QWI process in GaInNAs/GaAs multiquantum wells is induced mainly by the interdiffusion of In–Ga between the quantum wells and barriers. [ABSTRACT FROM AUTHOR]

High-quality GaInN(Sb)As/GaNAs double quantum wells (QWs) which emit at 1.54 μm wavelength at room temperature with a narrow linewidth of ∼34 meV (12 meV at 5 K) were fabricated by molecular-beam epitaxy on GaAs substrates. Photoluminescence and photoluminescence excitation spectroscopy were used to study the electronic states and optical properties of these heterostructures. By characterizing samples grown using different fluxes of Sb, the role played by Sb in the growth process and optical properties was elucidated. At low Sb flux, Sb atoms act mainly as a surfactant which improves the microstructure of the QWs and enhances the photoluminescence intensity. With an increase of Sb flux, some of the Sb atoms may incorporate into GaInNAs to form a quinary compound. In the latter case, the incorporation of Sb could also enhance the N composition in the QWs, which may be responsible for the further reduction of the band gap. [ABSTRACT FROM AUTHOR]

When lattice matched to GaN, the AlInN ternary alloy has a refractive index ∼7% lower than that of GaN. This characteristic can be exploited to perform in situ reflectometry during epitaxial growth of GaN-based multilayer structures on free-standing GaN substrates, by insertion of a suitable Al0.82In0.18N layer. The real-time information on growth rates and cumulative layer thicknesses thus obtainable is particularly valuable in the growth of optical resonant cavity structures. We illustrate this capability with reference to the growth of InGaN/GaN multiple quantum-well structures, including a doubly periodic structure with relatively thick GaN spacer layers between groups of wells. Al0.82In0.18N insertion layers can also assist in the fabrication of resonant cavity structures in postgrowth processing, for example, acting as sacrificial layers in a lift-off process exploiting etch selectivity between Al0.82In0.18N and GaN. [ABSTRACT FROM AUTHOR]

We report the fabrication of hybrid organic/inorganic semiconductor light-emitting devices that operate across the entire visible spectrum. The devices are based on a series of blue-, green-, and red-light-emitting polyfluorene materials that convert the emission from an array of micron-sized ultraviolet InGaN light-emitting diodes. We also demonstrate white-light-emitting versions of these hybrid devices by employing single films of carefully adjusted polyfluorene blends in which cascade energy transfer occurs between the constituent materials. The spectral and operating characteristics of the devices are described in detail. Such organic emission layer/inorganic light-emitting diode (LED) array based devices may provide a promising route to the fabrication of low-cost full-color microdisplays and other instrumentation devices. [ABSTRACT FROM AUTHOR]

We report the temperature-dependent photoluminescence characterization of InNxAs1-x/In0.53Ga0.47As/InP multiple quantum wells with various N contents emitting in the midinfrared wavelength range. The emission wavelength in this material system can be tuned by the N content, but the bowing effect is much weaker than in GaNAs. The correlation between the optical properties and the interface quality is demonstrated by examining the barrier-related emission. The role played by N is elucidated by comparing quantum well samples having either zero, low (0.25%) or high (5%) N content. [ABSTRACT FROM AUTHOR]

We report on the effects of combined strain-compensating and strain-mediating layers of various widths on the optical properties of 1.3 μm GaInNAs/GaAs single quantum well structures grown by metalorganic vapor phase epitaxy (MOVPE). While the emission wavelength of GaInNAs/GaAs quantum wells can be redshifted by the adoption of strain-compensated GaNAs layers, the material quality is degraded by the increased stress at the well/barrier interface. This detrimental effect can be cured by inserting a strain-mediating InGaAs layer between them. Contrary to what is expected, however, the emission wavelength is blueshifted by the insertion of the InGaAs layer, which is attributed to the reduced N incorporation due to the improved interface quality. Our results indicate that the optical properties of MOVPE-grown GaInNAs/GaAs quantum wells can be optimized in quantum efficiency and emission wavelength by combination of strain-compensating and strain-mediating layers with suitable characteristics. [ABSTRACT FROM AUTHOR]

We report the integration of a UV-curable polymer microlens array onto a matrix-addressable, 368-nm-wavelength, light-emitting diode device containing 64×64 micropixel elements. The geometrical and optical parameters of the microlenses were carefully chosen to allow the highly divergent emission from each micropixel to be collimated into a narrow beam of about 8-μm diam, over a distance of more than 500 μm. This device is demonstrated as a photolithographic exposure tool, where the pattern-programmable array plays the role both of light source and photomask. A simple pattern comprised of two disks having 16-μm diam and 30-μm spacing was transferred into an i-line photoresist. [ABSTRACT FROM AUTHOR]

We report optical studies of high-quality 1.3 μm strain-compensated GaInNAs/GaAs single-quantum-well structures grown by metalorganic vapor phase epitaxy. Photoluminescence excitation (PLE) spectroscopy shows clearly the electronic structure of the two-dimensional quantum well. The transition energies between quantized states of the electrons and holes are in agreement with theoretical calculations based on the band anti-crossing model in which the localized N states interact with the extended states in the conduction band. We also investigated the polarization properties of the luminescence by polarized edge-emission measurements. Luminescence bands with different polarization characters arising from the electron to heavy-hole and light-hole transitions, respectively, have been identified and verify the transition assignment observed in the PLE spectrum. [ABSTRACT FROM AUTHOR]

The electrical and optical characteristics of a 370 nm AlGaN light-emitting diode based on a microring geometry is presented. By structuring the light emission area into an interconnected array of microscale rings, current spreading in the n-type cladding layers is improved. A reduction of differential series resistance is observed, and the device saturates at a higher current as the carriers are injected efficiently and uniformly across the junction areas. As a result, optical output power from the microring light-emitting diode is improved compared to a conventional device of broad area geometry. [ABSTRACT FROM AUTHOR]

The recent development of high-density, two-dimensional arrays of micrometer-sized InGaN/GaN light-emitting diodes (micro-LEDs) with potential applications from scientific instrumentation to microdisplays has created an urgent need for controlled manipulation of the light output from these devices. With directed light output these devices can be used in situations where collimated beams or light focused onto several thousand matrix points is desired. In order to do this effectively, the emission characteristics of the devices must be fully understood and characterized. Here we utilize confocal microscopy to directly determine the emission characteristics and angular beam divergences from the individual micro-LED elements. The technique is applied to both top (into air) and bottom (through substrate) emission in arrays of green (540 nm), blue (470 nm), and UV (370 nm) micro-LED devices, at distances of up to 50 μm from the emission plane. The results are consistent with simple optical modeling of the expected beam profiles. [ABSTRACT FROM AUTHOR]

A technique based on the Fresnel diffraction effect for the fabrication of nano-scale site-controlled ring structures in InGaN/GaN multi-quantum well structures has been demonstrated. The ring structures have an internal diameter of 500 nm and a wall width of 300 nm. A 1 cm-1 Raman shift has been measured, signifying substantial strain relaxation from the fabricated structure. The 9 nm blueshift observed in the cathodoluminescence spectra can be attributed to band filling and/or screening of the piezoelectric field. A light emitting diode based on this geometry has been demonstrated. [ABSTRACT FROM AUTHOR]

Using the method of photoresist reflow and inductively coupled plasma dry etching, we have fabricated microlens arrays in type-IIa natural single-crystal diamond, with diameters down to 10 μm. The surface profile of the microlenses was characterized by atomic force microscopy and was found to match well with a spherical shape, with a surface roughness of better than 1.2 nm. To characterize the optical properties of these diamond microlens arrays, a laser scanning reflection/transmission confocal microscopy technique has been developed. This technique enabled the surface profile of the microlenses to be measured simultaneously with optical parameters including focal length and spot size, opening up an application area for confocal microscopy. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A size-dependent strain relaxation and its effects on the optical properties of InGaN/GaN multiple quantum wells (QWs) in micro-pillars have been investigated through a combination of high spatial resolution cathodoluminescence (CL) hyperspectral imaging and numerical modeling. The pillars have diameters (d) ranging from 2 to 150 μm and were fabricated from a III-nitride light-emitting diode (LED) structure optimized for yellow-green emission at ∼560 nm. The CL mapping enables us to investigate strain relaxation in these pillars on a sub-micron scale and to confirm for the first time that a narrow (≤2 μm) edge blue-shift occurs even for the large InGaN/GaN pillars (d > 10 μm). The observed maximum blue-shift at the pillar edge exceeds 7 nm with respect to the pillar centre for the pillars with diameters in the 2-16 μm range. For the smallest pillar (d = 2 μm), the total blue-shift at the edge is 17.5 nm including an 8.2 nm 'global' blue-shift at the pillar centre in comparison with the unetched wafer. By using a finite element method with a boundary condition taking account of a strained GaN buffer layer which was neglected in previous simulation works, the strain distribution in the QWs of these pillars was simulated as a function of pillar diameter. The blue-shift in the QWs emission wavelength was then calculated from the strain-dependent changes in piezoelectric field, and the consequent modification of transition energy in the QWs. The simulation and experimental results agree well, confirming the necessity for considering the strained buffer layer in the strain simulation. These results provide not only significant insights into the mechanism of strain relaxation in these micro-pillars but also practical guidance for design of micro/nano LEDs. [ABSTRACT FROM AUTHOR]

Light-emitting diodes (LEDs) based on an interconnected array of GaN/InGaN micro-ring elements have been demonstrated. The devices have electrical characteristics similar to those of conventional broad-area devices. However, due to the large surface areas provided by the sidewalls, the extraction efficiency is greatly enhanced. Intense light emission at the periphery of the micro-rings is observed upon excitation by an electron beam, suggesting scattering of the photons which are extracted through the sidewalls. The devices provide a doubling in total light output compared to a broad-area reference LED of equal light-generation area. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report an investigation of selective quantum-well intermixing (QWI) in 1.3-μm GaInNAs/GaAs multi quantum wells by silica-cap-induced disordering processes. After thermal annealing under specific conditions, controlled shifts of band gap at room temperature of over 200 nm have been observed in sputtered SiO[SUB2]-capped samples, while uncapped and SiO[SUB2]-capped samples by) plasma-enhanced chemical vapor deposition demonstrated negligible shift. This selective modification of the band gap in GaInNAs quantum wells has been confirmed by detailed photoluminescence and photoluminescence excitation spectroscopy, and by secondary ion mass spectrometry. The controlled tuning of the band gap of GaInNAs/GaAs by QWI is important for a wide range of photonic integrated circuits and advanced device applications. [ABSTRACT FROM AUTHOR]

We report on the nitrogen-concentration dependence of optical transitions between quantized states of electrons and holes in GaInNAs/GaAs multi-quantum wells. Using low-temperature photoluminescence excitation spectroscopy, systematic studies have been performed on a series of samples with nitrogen concentrations in the range 0%-1.14%. The observed data were compared with theoretical fitting based on the band anticrossing model in which the localized N states interact with the extended states in the conduction band, taking strain effects into account. Our results are consistent with the band anticrossing model, but with differing coupling strength between different quantum states of electrons in the quantum wells. [ABSTRACT FROM AUTHOR]

The effect of an etch-back step to control the cavity length within GaN-based microcavities formed between two dielectric Bragg mirrors was investigated using photoluminescence and reflectivity. The structures are fabricated using a combination of a laser lift-off technique to separate epitaxial III-N layers from their sapphire substrates and electron-beam evaporation to deposit silica/zirconia multilayer mirrors. The photoluminescence measurements reveal cavity modes from both etched and nonetched microcavities. Similar cavity finesses are measured for 2.0 and 0.8 μm GaN cavities fabricated from the same wafer, indicating that the etchback has had little effect on the microcavity quality. For InGaN quantum well samples the etchback is shown to allow controllable reduction of the cavity length. Two etch steps of 100 nm are demonstrated with an accuracy of approximately 5%. The etchback, achieved using inductively coupled plasma and wet chemical etching, allows removal of the low-quality GaN nucleation layer, control of the cavity length, and modification of the surface resulting from lift-off. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We investigate the electronic states in strained Ga[sub 0.62]In[sub 0.38]N[sub 0.015]As[sub 0.985]/GaAs multiple- quantum-well structures using photoluminescence and (polarized) photoluminescence excitation measurements at low temperature. From a theoretical fit to the experimental data, a type-I band alignment for the heavy holes with a strained conduction-band offset ratio of about 80% is obtained, while the light holes show an approximately flat band alignment. Additionally, our results suggest an increased effective electron mass in GaInNAs, possibly due to the interaction of the conduction band with nitrogen-related resonant states, an observation prospectively of benefit for GaInNAs-based diode lasers. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]